SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    9899, 9900, 9901, 9903, 9972, 9973, 9975, 
    9976, 9977, 9978, 9979, 9984, 9985, 
    9986, 9987, 9988, 9989, 9990, 9991, 
    9992
  )

Query time 0.00077

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 (9899,9900,9901,9903,9972,9973,9975,9976,9977,9978,9979,9984,9985,9986,9987,9988,9989,9990,9991,9992)"
    }
  }
}