SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'db5a3fb60d498bb5e4cc8c29d5f39b2a16d43dc33de61f7bb49794afa57f0436' 
  AND token = 'zUOjkmeXMWWO3pYwc/8f/1YrzqICEyqtPQdLBKy5teU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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