is it possible to have a transaction confirmed in few sec
The fastest that you can have it confirmed is in the next block, which can happen anytime. From the next second now to even two hours after. You will have to select the highest fee, though, which as we speak is 43 sat/vb (and use RBF in case that's become less than the highest).
by saying final i meant with no possibility to rteplace it with another one
Only if it's confirmed. If it's 0-conf, it can be double-spent with another 0-conf.