SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '399201ed9cc29c9604fb3ad87ab5c30282c385caf5ac5dfe41905dd44a6d515a' 
  AND token = 'd9RtQgWsiaM4VFbkK9cGj0iQ6B5745uReb4WEzTijrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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