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 (
    25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 
    36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 
    46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 
    56, 57, 58, 59, 60, 62, 63, 64, 65, 67, 
    68, 69, 70, 71, 72, 73, 74, 75, 76, 4
  )

Query time 0.00064

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "g",
      "access_type": "system",
      "possible_keys": ["PRIMARY"],
      "rows": 1,
      "filtered": 100
    },
    "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": ["const"],
      "rows": 2,
      "filtered": 100
    },
    "block-nl-join": {
      "table": {
        "table_name": "p",
        "access_type": "ALL",
        "possible_keys": ["PRIMARY", "idx_group_id"],
        "rows": 7,
        "filtered": 100,
        "attached_condition": "p.group_id = 10 and p.product_id in (25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,62,63,64,65,67,68,69,70,71,72,73,74,75,76,4)"
      },
      "buffer_type": "flat",
      "buffer_size": "1Kb",
      "join_type": "BNL"
    }
  }
}