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 (
    6958, 6960, 6968, 6961, 6964, 6957, 6956, 
    6954, 6955, 6948, 3914, 3913, 6950, 
    6949, 3477, 3452, 3478, 3479, 3453, 
    3491, 3488, 3497, 3495, 3489, 3492, 
    3496, 3490, 3494, 6951, 3502, 3503, 
    3493, 3498, 3428, 3433, 3432, 12594, 
    12609, 12424, 12554, 12536, 12546, 
    13127, 12464, 12624, 12654, 13148, 
    13153
  )

Query time 0.00128

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "177.76"
    },
    "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": 51,
          "rows_produced_per_join": 51,
          "filtered": "100.00",
          "index_condition": "(`test2_gaseus`.`p`.`product_id` in (6958,6960,6968,6961,6964,6957,6956,6954,6955,6948,3914,3913,6950,6949,3477,3452,3478,3479,3453,3491,3488,3497,3495,3489,3492,3496,3490,3494,6951,3502,3503,3493,3498,3428,3433,3432,12594,12609,12424,12554,12536,12546,13127,12464,12624,12654,13148,13153))",
          "cost_info": {
            "read_cost": "29.86",
            "eval_cost": "5.10",
            "prefix_cost": "34.96",
            "data_read_per_join": "816"
          },
          "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": 51,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "12.75",
            "eval_cost": "5.10",
            "prefix_cost": "52.81",
            "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": 357,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "89.25",
            "eval_cost": "35.70",
            "prefix_cost": "177.76",
            "data_read_per_join": "36K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}