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 (
    126021, 131644, 142748, 149098, 151106, 
    140421, 176351, 176104, 122713, 131185, 
    123527, 161448
  )

Query time 0.00050

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.045543227,
    "nested_loop": [
      {
        "table": {
          "table_name": "p",
          "access_type": "index",
          "possible_keys": ["PRIMARY", "idx_group_id"],
          "key": "idx_parent_product_id",
          "key_length": "3",
          "used_key_parts": ["parent_product_id"],
          "loops": 1,
          "rows": 39,
          "cost": 0.012366635,
          "filtered": 30.76922989,
          "attached_condition": "p.product_id in (126021,131644,142748,149098,151106,140421,176351,176104,122713,131185,123527,161448)",
          "using_index": true
        }
      },
      {
        "table": {
          "table_name": "g",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["id"],
          "ref": ["u985510652_ecartify_abhi.p.group_id"],
          "loops": 12,
          "rows": 1,
          "cost": 0.01155248,
          "filtered": 100
        }
      },
      {
        "block-nl-join": {
          "table": {
            "table_name": "f",
            "access_type": "ALL",
            "possible_keys": ["idx_group_id"],
            "loops": 12,
            "rows": 5,
            "cost": 0.021624112,
            "filtered": 40
          },
          "buffer_type": "flat",
          "buffer_size": "5KiB",
          "join_type": "BNL",
          "attached_condition": "f.group_id = p.group_id"
        }
      }
    ]
  }
}