SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '578fd3de6e5c13b633404b553772a0320a9abc350b3c326730b5cea7e328276c' 
  AND token = 'ojVNi5+EUwxAihUxSGCDdWBKvvwKl1O0EIs1OWpDGFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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