Sort of like “deriving their just powers from the consent of the governed.” Did you consent to the Constitution? I didn’t. I was born under it. When do we get to vote on it?
Vote with your feet - and I invite all who disagree with the constitution to take this route (hear that, Obama??) - seek out a country with a governing system that is more appealing and move there.
The founders are stating an idealistic principle of government, that the just powers of government (my take on "just" is having a basis other than brute force) derive from the governed. Even the (sane) guilty will agree they deserve to be punished or pay for their action.
It describes a quality of the government, not that all individuals perform a "sign on" ceremony to show consent.
As for voting on it, I can imagine a just government that limits the vote; and we are witnesses to the history of social decline when "voting" is held out as a substitute for "consent leading to a just government."