SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ef724b8c0fdf6a0fca151a0953a7d3264bc2b564a2588a5bed9efe070aeb05b' 
  AND token = '39zd1+CEZXwSvvRjbUNHQHZxbAoWCMkYngkD/7e0Rp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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