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 (
    12664, 12667, 12666, 12751, 2641, 2642, 
    2635, 2636, 12691, 12690, 12692, 2199, 
    2200, 2237, 12678, 3238, 3237, 12656, 
    13107, 12672, 12671, 11136, 2772, 11808
  )

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "p",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "idx_group_id"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 24,
      "filtered": 100,
      "index_condition": "p.product_id in (12664,12667,12666,12751,2641,2642,2635,2636,12691,12690,12692,2199,2200,2237,12678,3238,3237,12656,13107,12672,12671,11136,2772,11808)"
    },
    "table": {
      "table_name": "g",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["id"],
      "ref": ["ymonline_livedata.p.group_id"],
      "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": ["ymonline_livedata.p.group_id"],
      "rows": 1,
      "filtered": 100
    }
  }
}

Result

feature_id purpose product_id parent_product_id id code
568 group_variation_catalog_item 3237 0 374 LEPOC8