SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42e34a19f7541f2a99e8d9276bff529c923e21ebd39077ac67f6056257ffbb74' 
  AND token = '8LFYh3RBJw0nEfyKTWV8y2GNeyd7Ldn+YBl+y+XBKhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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