SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2de99e0e4f4f1895c57345615cdbfdcc271f588a2d303798663451ca25543e8' 
  AND token = 'C5SBid1n5rBlT+LpZXTOXxWISaU+OPgNIoTeDLWXn54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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