You can control these in Chrome by clicking menu > Settings > Search engine > Manage search engines. The "Keyword" field defines the custom keyword that launches a custom search. Add a short one to speed things up.

Go into Chrome settings, search for search to find "Manage Search Engines". There you will probably find many already defined (I appear to have a couple hundred), as well as a link to official Chrome documentation. You need to scroll down to the bottom to see what the columns mean: they are name, keyword, and search URL.

Manage Existing Keyword Shortcuts If you’d like to change what sites Chrome automatically lets you search or add another site and keyword to the list, right-click the address bar and select Edit search engines. Alternately, open the Options dialog and click Manage beside the Default Search option. This will open the list of your search engines.