Sometimes I want to ask a question, but I am afraid that not many users are active in the moment.
That's a valid concern, but the other side of the coin is that there a not many users who are posting questions at that moment. So the users who are active have more chance to view your question.
It turns out that on average, both effect cancel each other out. I demonstrated something similar a year ago on Meta Stack Overflow. That was inspired by a slightly different question (weekday vs. weekend attention). Still, according to this query, there's no visible trend. While the number of questions (blue line) peaks every day around 16:00 UTC, the average # of views per question (orange line) behaves erratically and shows no pattern.