The social contract theory is a just-so story. It's not real. Governments exist because they are a tool for concentrating power and out-compete other social groupings in terms of economic strength and capacity for violence. But good governments want to incentive happy, productive citizens, so they use pre-existing language, or invent new language, to discuss how to achieve that. "Rights" are an example of this.
Governments don't exist from the consent of the governed, but rather from the lack of force sufficiently strong to dissolve them. Just because I don't have this force doesn't mean I have consented to being governed.