SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5846e861661d2b55317863d32304a14ec504fdf54c5ccf4d70d42a2706041a9' 
  AND token = '9gzBQFtHWfQcHrKY5ZHtWUgNeyVAgbhF1pCf6qiEuvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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