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 (
    6959, 3425, 6958, 6960, 13127, 12464, 
    12624, 12654, 13148, 13153, 12928
  )

Query time 0.00068

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "45.01"
    },
    "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": 13,
          "rows_produced_per_join": 13,
          "filtered": "100.00",
          "index_condition": "(`test2_gaseus`.`p`.`product_id` in (6959,3425,6958,6960,13127,12464,12624,12654,13148,13153,12928))",
          "cost_info": {
            "read_cost": "7.31",
            "eval_cost": "1.30",
            "prefix_cost": "8.61",
            "data_read_per_join": "208"
          },
          "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": 13,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "3.25",
            "eval_cost": "1.30",
            "prefix_cost": "13.16",
            "data_read_per_join": "5K"
          },
          "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": 91,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "22.75",
            "eval_cost": "9.10",
            "prefix_cost": "45.01",
            "data_read_per_join": "9K"
          },
          "used_columns": [
            "feature_id",
            "purpose",
            "group_id"
          ]
        }
      }
    ]
  }
}