SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    68, 1204, 453, 1251, 1250, 1249, 1248, 
    1247, 1246, 1245, 1244, 1243
  )

Query time 0.00090

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 12,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (68,1204,453,1251,1250,1249,1248,1247,1246,1245,1244,1243)"
    }
  }
}