SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    9894, 9895, 9896, 9897, 9899, 9900, 9901, 
    9903, 9838, 9839, 9840, 9841, 9842, 
    9843, 9844, 9845, 9846, 9847, 9848, 
    9849
  )

Query time 0.00336

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 (9894,9895,9896,9897,9899,9900,9901,9903,9838,9839,9840,9841,9842,9843,9844,9845,9846,9847,9848,9849)"
    }
  }
}