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 (
    13951, 13952, 13953, 13954, 13955, 13956, 
    13957, 13958, 13959, 13960, 13961, 
    13962
  )

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.0488662,
    "nested_loop": [
      {
        "table": {
          "table_name": "p",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "idx_group_id"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "loops": 1,
          "rows": 12,
          "cost": 0.0138334,
          "filtered": 100,
          "attached_condition": "p.product_id in (13951,13952,13953,13954,13955,13956,13957,13958,13959,13960,13961,13962)"
        }
      },
      {
        "table": {
          "table_name": "f",
          "access_type": "ref",
          "possible_keys": ["idx_group_id"],
          "key": "idx_group_id",
          "key_length": "3",
          "used_key_parts": ["group_id"],
          "ref": ["u508912950_dev_2025.p.group_id"],
          "loops": 12,
          "rows": 1,
          "cost": 0.02348032,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "g",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["id"],
          "ref": ["u508912950_dev_2025.p.group_id"],
          "loops": 12,
          "rows": 1,
          "cost": 0.01155248,
          "filtered": 100
        }
      }
    ]
  }
}