ISP can very easily see what you searched for even with SSL. SSL encrypts the TRAFFIC so they can't see the content of the webpages, But your search terms are right there naked in the URL even though it is https secured. This is unfortunately the case for Google, Bing and even DuckDuckGo. Try it and you can see for yourself.

At least DDG offers in their options to scramble the URL but one has to know about that feature AND enable it. It is in their settings under Privacy and you have to turn OFF GET (2nd option). https://duckduckgo.com/settings#