SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4247a483014c7584df82fc150ddfdd399349ff0a3f8f56609f068bbb1251ae26' 
  AND token = 'WDvJKUFWnmZ0PUt+QknhXuxV4qUYD41fELkZJlF/6AI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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