SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    21699, 21694, 21695, 21697, 21696, 21698, 
    21691, 21692, 21690, 21693, 21687, 
    21688, 21715, 21683, 21685, 21724, 
    21686, 21684, 21689, 21717, 21716, 
    21719, 21718, 21721
  )

Query time 0.00119

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": 24,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (21699,21694,21695,21697,21696,21698,21691,21692,21690,21693,21687,21688,21715,21683,21685,21724,21686,21684,21689,21717,21716,21719,21718,21721)"
    }
  }
}