SELECT 
  f.feature_id, 
  f.purpose, 
  p.product_id, 
  p.parent_product_id, 
  g.id, 
  g.code 
FROM 
  cscart_product_variation_group_features AS f 
  INNER JOIN cscart_product_variation_groups AS g ON f.group_id = g.id 
  INNER JOIN cscart_product_variation_group_products AS p ON f.group_id = p.group_id 
WHERE 
  p.product_id IN (
    4159, 4160, 4161, 4162, 4209, 4210, 4211, 
    4212, 4213, 4214, 4215, 3102, 3110, 
    6670, 6685, 6698, 3095, 3101, 3108, 
    6683, 6697, 12594, 12609, 3099, 19, 
    20, 21, 3929, 3930, 3931, 12424, 12554, 
    12536, 12546, 6724, 3100, 3106, 3114, 
    3120, 3125, 3153, 3154, 6672, 6688, 
    6689, 6694, 6702, 6706
  )

Query time 0.00096

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "171.26"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "p",
          "access_type": "range",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "product_id"
          ],
          "key_length": "3",
          "rows_examined_per_scan": 49,
          "rows_produced_per_join": 49,
          "filtered": "100.00",
          "index_condition": "(`test2_gaseus`.`p`.`product_id` in (4159,4160,4161,4162,4209,4210,4211,4212,4213,4214,4215,3102,3110,6670,6685,6698,3095,3101,3108,6683,6697,12594,12609,3099,19,20,21,3929,3930,3931,12424,12554,12536,12546,6724,3100,3106,3114,3120,3125,3153,3154,6672,6688,6689,6694,6702,6706))",
          "cost_info": {
            "read_cost": "29.16",
            "eval_cost": "4.90",
            "prefix_cost": "34.06",
            "data_read_per_join": "784"
          },
          "used_columns": [
            "product_id",
            "parent_product_id",
            "group_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "g",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "id"
          ],
          "key_length": "3",
          "ref": [
            "test2_gaseus.p.group_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 49,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "12.25",
            "eval_cost": "4.90",
            "prefix_cost": "51.21",
            "data_read_per_join": "19K"
          },
          "used_columns": [
            "id",
            "code"
          ]
        }
      },
      {
        "table": {
          "table_name": "f",
          "access_type": "ref",
          "possible_keys": [
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "ref": [
            "test2_gaseus.p.group_id"
          ],
          "rows_examined_per_scan": 7,
          "rows_produced_per_join": 343,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "85.75",
            "eval_cost": "34.30",
            "prefix_cost": "171.26",
            "data_read_per_join": "34K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}