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 (
    189, 192, 168, 188, 166, 203, 196, 3, 165, 
    167, 221, 184, 193, 224, 160, 820, 169, 
    200
  )

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.07126534,
    "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": 18,
          "cost": 0.01994494,
          "filtered": 100,
          "attached_condition": "p.product_id in (189,192,168,188,166,203,196,3,165,167,221,184,193,224,160,820,169,200)"
        }
      },
      {
        "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": ["u428615623_ecartifygonje.p.group_id"],
          "loops": 18,
          "rows": 1,
          "cost": 0.03440128,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "g",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["id"],
          "ref": ["u428615623_ecartifygonje.p.group_id"],
          "loops": 18,
          "rows": 1,
          "cost": 0.01691912,
          "filtered": 100
        }
      }
    ]
  }
}