It is feasible that savvy cabin crew survived the 45000ft excursion
Not with a standard walkaround bottle and mask, even at high rate.
In a cabin above 40,000', surviving beyond a few seconds is a full time business involving pressure breathing and a real oxygen mask (like a fighter pilot would wear) with pressure breathing capability that pins the mask so tightly to the face with an overcentre lever, it's almost painful. If you're not familiar with the term 'pressure breathing', look it up; it's possibly on Wiki.
It would also, very quickly, become unbelievably cold. And I mean COLD, to the point of incapacitation.