Boardgaming is not a matter of life or death...
...it's much more important than that!
Re: Exact rules of the mist token
...In our local translated edition the text says that if you end your turn on mist token, you must open it up....
That is the confirmed rule from the designer. You can run through the mist as long as you are happy and see nothing. Only when you stop the mist catches up with you and you turn the token.
BTW you can use the scope also only when stopping, so even with it it is a slow walk through the mist to avoid surprises.