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 (
    2021, 2017, 2015, 1909, 1275, 1271, 1267, 
    1264, 1262, 1258, 1246, 1245, 1241, 
    1229, 1226, 1150, 1149, 1145, 1131, 
    1130, 1129, 1128, 1127, 1126, 1125, 
    1124, 1123, 1111, 1110, 1109, 1108, 
    1107, 1101, 1099, 1094, 1092, 1088, 
    1054, 1053, 1051, 1050, 1049, 1048, 
    967, 966, 965, 960, 959
  )

Query time 0.00054

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "68.36"
    },
    "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": "(`wearethehelpful_scalesta_net`.`p`.`product_id` in (2021,2017,2015,1909,1275,1271,1267,1264,1262,1258,1246,1245,1241,1229,1226,1150,1149,1145,1131,1130,1129,1128,1127,1126,1125,1124,1123,1111,1110,1109,1108,1107,1101,1099,1094,1092,1088,1054,1053,1051,1050,1049,1048,967,966,965,960,959))",
          "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": [
            "wearethehelpful_scalesta_net.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": [
            "wearethehelpful_scalesta_net.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": "68.36",
            "data_read_per_join": "4K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}