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 (
    337, 335, 334, 329, 330, 331, 325, 319, 
    320, 321, 322, 323, 318, 317, 306, 307, 
    308, 309, 310, 311, 312, 313, 314, 315, 
    316, 303, 304, 305, 302, 301, 300, 298, 
    293, 292, 291, 290, 287, 278, 280, 282, 
    247, 248, 241, 244, 245, 246, 240, 6
  )

Query time 0.00217

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "104.71"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "f",
          "access_type": "ALL",
          "possible_keys": [
            "idx_group_id"
          ],
          "rows_examined_per_scan": 13,
          "rows_produced_per_join": 13,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "2.11",
            "eval_cost": "2.60",
            "prefix_cost": "4.71",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      },
      {
        "table": {
          "table_name": "g",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "id"
          ],
          "key_length": "3",
          "ref": [
            "atulecarter_atul_demo1.f.group_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 13,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "13.00",
            "eval_cost": "2.60",
            "prefix_cost": "20.31",
            "data_read_per_join": "5K"
          },
          "used_columns": [
            "id",
            "code"
          ]
        }
      },
      {
        "table": {
          "table_name": "p",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "idx_group_id"
          ],
          "key": "idx_group_id",
          "used_key_parts": [
            "group_id"
          ],
          "key_length": "3",
          "ref": [
            "atulecarter_atul_demo1.f.group_id"
          ],
          "rows_examined_per_scan": 7,
          "rows_produced_per_join": 101,
          "filtered": "97.96",
          "cost_info": {
            "read_cost": "63.70",
            "eval_cost": "20.28",
            "prefix_cost": "104.71",
            "data_read_per_join": "1K"
          },
          "used_columns": [
            "product_id",
            "parent_product_id",
            "group_id"
          ],
          "attached_condition": "(`atulecarter_atul_demo1`.`p`.`product_id` in (337,335,334,329,330,331,325,319,320,321,322,323,318,317,306,307,308,309,310,311,312,313,314,315,316,303,304,305,302,301,300,298,293,292,291,290,287,278,280,282,247,248,241,244,245,246,240,6))"
        }
      }
    ]
  }
}