> Your question can wait, the world doesn't revolve around you, and value your coworkers time!
…right, but the world doesn't revolve around you either though. You should be willing to sacrifice your time to help your coworker and value their time as well.
Headphones, in my experience, tend to indicate a person is listening to audio, not that they don't want to be bothered by anyone. Maybe your expectations do not line up with societal norms? Just something to think about.
You could consider adding a visual indicator to your workspace that says "focused on something, please do not interrupt" or "available for questions". Our offices have little stoplight things by the door that can be used to tell someone whether or not it's a good time for an interruption. Having something easily visible like that can communicate more clearly to your coworkers that you're trying to focus without interrupting your focus.