SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe49223bc4309797393d249b001569022a3fb5a48bc908f1caeb100748a05fd8' 
  AND token = 'k4kDIFNfYyQGygLHdLs+4qvnV/pBqiS9yZV5i3pPaFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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