SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    12820, 12821, 12822, 12983, 10176, 12906, 
    12907, 12908, 12909, 10174, 12794, 
    12795, 12796, 10172, 12712, 12713
  )

Query time 0.00044

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": 16,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (12820,12821,12822,12983,10176,12906,12907,12908,12909,10174,12794,12795,12796,10172,12712,12713)"
    }
  }
}