If you use Chrome, you can configure a custom search engine so that you can get results by directly typing your search keyword in the address bar or "omnibox".
Go to the YouTube site, right-click within the search box and select Add As Search Engine... from the context menu.
In the dialog box that appears, the text boxes will be pre-filled. You can choose to change the value for the URL box to this -
https://www.youtube.com/results?search_sort=video_view_count&search_query=%s
You can change the value for the Keyword box to YT (or any other abbreviation) instead of youtube.com. When you wish to search for a video on YouTube, type YT in the Chrome address bar and then press space or tab followed by the keywords you want to search by.