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 (
    12928, 3135, 12850, 12869, 12752, 12802, 
    3403, 3404, 3405, 3406, 3408, 3409, 
    6930, 6931, 6932, 6933, 6934, 6935, 
    6936, 3407, 2666, 3845, 12796, 12797, 
    2667, 2668, 2669, 2670, 3846, 3847, 
    3848, 3849, 3850, 6258, 12795
  )

Query time 0.00126

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "122.51"
    },
    "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": 35,
          "rows_produced_per_join": 35,
          "filtered": "100.00",
          "index_condition": "(`test2_gaseus`.`p`.`product_id` in (12928,3135,12850,12869,12752,12802,3403,3404,3405,3406,3408,3409,6930,6931,6932,6933,6934,6935,6936,3407,2666,3845,12796,12797,2667,2668,2669,2670,3846,3847,3848,3849,3850,6258,12795))",
          "cost_info": {
            "read_cost": "21.01",
            "eval_cost": "3.50",
            "prefix_cost": "24.51",
            "data_read_per_join": "560"
          },
          "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": 35,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "8.75",
            "eval_cost": "3.50",
            "prefix_cost": "36.76",
            "data_read_per_join": "13K"
          },
          "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": 245,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "61.25",
            "eval_cost": "24.50",
            "prefix_cost": "122.51",
            "data_read_per_join": "24K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}