You're mixing terms. The youngest you can retire with benefits is age 55. You are fully vested after 5 years of employment and you can stop working anytime after that and retain your benefits - now the earliest you can exercise them is 55 with the penalty or age 60 for normal.

So yes, you can stop working at age 40, go find another job or whatever, and take whatever you have and begin normal benefits at age 60.