AK fold in level 1

[Allinlife]

10+1 PP
level 1, mostly even stacks, UTG+2 goes allin for 350
MP beside him just calls it, and I have AKo right beside MP

normally, I'd raise allin if it wasn't for MP calling(is this wrong?)

I laid it down because :
-limps like those usually sign big hands (AA/KK)
-I had not invested in the pot
-only level 1, with my healthy stack

what's the optimal move? (and would raising allin be a good move if MP had folded? auto fold if MP goes allin?)

thanks.