SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    12549, 12581, 12557, 12558, 12570, 12578, 
    12568, 12547, 12569, 12584, 12592, 
    12575, 12574, 12550, 12544, 12564, 
    12577, 12579, 12555, 12560
  )

Query time 0.00088

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": 20,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (12549,12581,12557,12558,12570,12578,12568,12547,12569,12584,12592,12575,12574,12550,12544,12564,12577,12579,12555,12560)"
    }
  }
}