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 (
    1341, 1342, 1856, 2913, 1815, 1819, 2914, 
    1859, 1858, 1850, 1294, 1298, 1297, 
    1293, 1295, 1814, 1816, 1817, 1818, 
    1820, 1821, 1822, 1823, 1824
  )

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.02544425,
    "nested_loop": [
      {
        "table": {
          "table_name": "g",
          "access_type": "index",
          "possible_keys": ["PRIMARY"],
          "key": "idx_group_code",
          "key_length": "387",
          "used_key_parts": ["code"],
          "loops": 1,
          "rows": 2,
          "cost": 0.00693929,
          "filtered": 100,
          "using_index": true
        }
      },
      {
        "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": ["u985510652_ecartify_dev.g.id"],
          "loops": 2,
          "rows": 1,
          "cost": 0.00527872,
          "filtered": 100
        }
      },
      {
        "table": {
          "table_name": "p",
          "access_type": "ref",
          "possible_keys": ["PRIMARY", "idx_group_id"],
          "key": "idx_group_id",
          "key_length": "3",
          "used_key_parts": ["group_id"],
          "ref": ["u985510652_ecartify_dev.g.id"],
          "loops": 2,
          "rows": 5,
          "cost": 0.01322624,
          "filtered": 100,
          "index_condition": "p.product_id in (1341,1342,1856,2913,1815,1819,2914,1859,1858,1850,1294,1298,1297,1293,1295,1814,1816,1817,1818,1820,1821,1822,1823,1824)"
        }
      }
    ]
  }
}