SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    9976, 9977, 9978, 9979, 9954, 9955, 9956, 
    9957, 9958, 9959, 9960, 9961, 9962, 
    9963, 9964, 9965, 9966, 9967, 9968, 
    9969
  )

Query time 0.00126

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 (9976,9977,9978,9979,9954,9955,9956,9957,9958,9959,9960,9961,9962,9963,9964,9965,9966,9967,9968,9969)"
    }
  }
}