SELECT 
  cscart_products_categories.product_id, 
  GROUP_CONCAT(
    IF(
      cscart_products_categories.link_type = "M", 
      CONCAT(
        cscart_products_categories.category_id, 
        "M"
      ), 
      cscart_products_categories.category_id
    )
  ) AS category_ids, 
  product_position_source.position AS position 
FROM 
  cscart_products_categories 
  INNER JOIN cscart_categories ON cscart_categories.category_id = cscart_products_categories.category_id 
  AND cscart_categories.storefront_id IN (0, 1) 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  LEFT JOIN cscart_products_categories AS product_position_source ON cscart_products_categories.product_id = product_position_source.product_id 
  AND product_position_source.category_id = 266 
WHERE 
  cscart_products_categories.product_id IN (
    4115, 4116, 4149, 4150, 4151, 4152, 4153, 
    4154, 4155, 4202, 4203, 4204, 4205, 
    4206, 4207, 4208, 3109, 3123, 6671, 
    6676, 6684, 5, 6, 7, 8, 9, 10, 11, 57, 58, 
    59, 60, 61, 62, 63, 111, 112, 113, 114, 
    115, 116, 117, 210, 211, 212, 213, 214, 
    215, 216, 217, 218, 219, 220, 221, 222, 
    223, 278, 279, 280, 281, 282, 283, 284, 
    332, 333, 334, 335, 336, 337, 3915, 3916, 
    3917, 3918, 3919, 3920, 3921, 3968, 
    3969, 3970, 3971, 3972, 3973, 3974, 
    4020, 4021, 4022, 4023, 4024, 4025, 
    4026, 4094, 4095, 4096, 4097, 4098, 
    4099
  ) 
GROUP BY 
  cscart_products_categories.product_id

Query time 0.00347

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "61.16"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "1.76"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "cscart_categories",
            "access_type": "ALL",
            "possible_keys": [
              "PRIMARY",
              "c_status",
              "p_category_id"
            ],
            "rows_examined_per_scan": 46,
            "rows_produced_per_join": 1,
            "filtered": "4.00",
            "cost_info": {
              "read_cost": "5.15",
              "eval_cost": "0.18",
              "prefix_cost": "5.33",
              "data_read_per_join": "7K"
            },
            "used_columns": [
              "category_id",
              "storefront_id",
              "usergroup_ids",
              "status"
            ],
            "attached_condition": "((`test2_gaseus`.`cscart_categories`.`storefront_id` in (0,1)) and ((`test2_gaseus`.`cscart_categories`.`usergroup_ids` = '') or (0 <> find_in_set(0,`test2_gaseus`.`cscart_categories`.`usergroup_ids`)) or (0 <> find_in_set(1,`test2_gaseus`.`cscart_categories`.`usergroup_ids`))) and (`test2_gaseus`.`cscart_categories`.`status` in ('A','H')))"
          }
        },
        {
          "table": {
            "table_name": "cscart_products_categories",
            "access_type": "ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id"
            ],
            "key_length": "3",
            "ref": [
              "test2_gaseus.cscart_categories.category_id"
            ],
            "rows_examined_per_scan": 83,
            "rows_produced_per_join": 1,
            "filtered": "1.15",
            "index_condition": "(`test2_gaseus`.`cscart_products_categories`.`product_id` in (4115,4116,4149,4150,4151,4152,4153,4154,4155,4202,4203,4204,4205,4206,4207,4208,3109,3123,6671,6676,6684,5,6,7,8,9,10,11,57,58,59,60,61,62,63,111,112,113,114,115,116,117,210,211,212,213,214,215,216,217,218,219,220,221,222,223,278,279,280,281,282,283,284,332,333,334,335,336,337,3915,3916,3917,3918,3919,3920,3921,3968,3969,3970,3971,3972,3973,3974,4020,4021,4022,4023,4024,4025,4026,4094,4095,4096,4097,4098,4099))",
            "cost_info": {
              "read_cost": "38.18",
              "eval_cost": "0.18",
              "prefix_cost": "58.78",
              "data_read_per_join": "28"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "link_type"
            ]
          }
        },
        {
          "table": {
            "table_name": "product_position_source",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "pt"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "category_id",
              "product_id"
            ],
            "key_length": "6",
            "ref": [
              "const",
              "test2_gaseus.cscart_products_categories.product_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 1,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "0.44",
              "eval_cost": "0.18",
              "prefix_cost": "59.40",
              "data_read_per_join": "28"
            },
            "used_columns": [
              "product_id",
              "category_id",
              "position"
            ]
          }
        }
      ]
    }
  }
}