is it possible for an indexed page to never be returned to user search queries?
"Never" is a pretty broad word in this case. At some point, an indexed page will be returned to a given query. The more words in the query that match words or phrases on the page, the more likely it will be shown in a result. If someone targets your domain using the site: command in Google, the chances go up dramatically that a page will be returned.
To extend the hypothetical to the maximum silliness, let us assume you have a page with nothing but
dfvldfmvl sfjvnsafgnva weaugnaoweiun
as the content. This could possibly be a page that Google would never return as a result because unless the user is searching by spastically banging their head into the keyboard the odds on entering a query that would match one of the above strings is pretty remote. However, don't discount Google's "Did you mean?" search result to return garbage against garbage and thus somehow return a page with the above text in response to a random character search for wholly different characters.
If you are worried about a page getting indexed that shouldn't be, a simple adjustment to your robots.txt will take care of that. If you are concerned that a page should be coming up in response to certain terms but isn't, that's a whole other thing and likely means your SEO, isn't.