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 (
    1668, 1669, 1670, 1671, 2220, 2221, 2222, 
    2223, 5353, 5354, 5355, 5356, 5357, 
    5358, 5359, 5360, 5361, 5362, 5363, 
    5364, 5365, 5366, 5367, 5368, 5369, 
    5370, 5820, 5821, 5822, 5823, 12916, 
    12921, 12876, 12896, 12900, 12909
  )

Query time 0.00187

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "126.01"
    },
    "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": 36,
          "rows_produced_per_join": 36,
          "filtered": "100.00",
          "index_condition": "(`test2_gaseus`.`p`.`product_id` in (1668,1669,1670,1671,2220,2221,2222,2223,5353,5354,5355,5356,5357,5358,5359,5360,5361,5362,5363,5364,5365,5366,5367,5368,5369,5370,5820,5821,5822,5823,12916,12921,12876,12896,12900,12909))",
          "cost_info": {
            "read_cost": "21.61",
            "eval_cost": "3.60",
            "prefix_cost": "25.21",
            "data_read_per_join": "576"
          },
          "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": 36,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "9.00",
            "eval_cost": "3.60",
            "prefix_cost": "37.81",
            "data_read_per_join": "14K"
          },
          "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": 252,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "63.00",
            "eval_cost": "25.20",
            "prefix_cost": "126.01",
            "data_read_per_join": "25K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}