When you say keywords, do you mean words in the URL or on the website but not in the URL?
You can use the web filter to block keywords in the URL, for example if you want to block “malware” then you need to make a category, add the rule for website “malware” to the category and then add that category to the Blocked Sites rule.
Sounds funny, but I didn’t know about that! Silly me. Will explore that in more details and write here if it is not something I think might be useful to implement. Thanks a lot again and sorry for wasting your time.