SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    12527, 12521, 13099, 12514, 12513, 12499, 
    12500, 12506, 12508, 12522, 12507, 
    13100, 12503, 12529, 12515, 12525, 
    12532, 12523, 12517, 12509
  )

Query time 0.00087

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 (12527,12521,13099,12514,12513,12499,12500,12506,12508,12522,12507,13100,12503,12529,12515,12525,12532,12523,12517,12509)"
    }
  }
}