SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de8a323aa303ffa85a9cde3bc1e051ebd2ad4194516e5b379f675a66691c8557' 
  AND token = 'NU0MnHqmTNdeDGHK1br5L0X1leZirZDTo1SKoneTPDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}