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 (
    3470, 3457, 3462, 3450, 3458, 3463, 3451, 
    3445, 3472, 3481, 3482, 3475, 3483, 
    3474, 3473, 3426, 6949, 3427, 3477, 
    3452, 3478, 3479, 3453, 3491, 3488, 
    3497, 3495, 3489, 3492, 3496, 3490, 
    3494, 6951, 3502, 3503, 3493, 3498, 
    3428, 12916, 12921, 12876, 12896, 12900, 
    12909
  )

Query time 0.00101

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "154.01"
    },
    "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": 44,
          "rows_produced_per_join": 44,
          "filtered": "100.00",
          "index_condition": "(`test2_gaseus`.`p`.`product_id` in (3470,3457,3462,3450,3458,3463,3451,3445,3472,3481,3482,3475,3483,3474,3473,3426,6949,3427,3477,3452,3478,3479,3453,3491,3488,3497,3495,3489,3492,3496,3490,3494,6951,3502,3503,3493,3498,3428,12916,12921,12876,12896,12900,12909))",
          "cost_info": {
            "read_cost": "26.41",
            "eval_cost": "4.40",
            "prefix_cost": "30.81",
            "data_read_per_join": "704"
          },
          "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": 44,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "11.00",
            "eval_cost": "4.40",
            "prefix_cost": "46.21",
            "data_read_per_join": "17K"
          },
          "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": 308,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "77.00",
            "eval_cost": "30.80",
            "prefix_cost": "154.01",
            "data_read_per_join": "31K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}