The smallest physically relevant distance is one Planck length. The smallest physically relevant time measure is one Planck time. Combine those two and you get the smallest 'distance' light can propagate in modern physics, one Planck length in one Planck time.

If you were able to observe such a thing happen you would be 'frozen in time'. No brain activity and no 'life' as I see it as you would watch the smallest instant of 'time' possible. So you can't. And to pass beyond that is a theoretical exercise I will leave to the true believers of 'time travels'.

Because we live in 'SpaceTime' according to Einstein. There everything is a function of each other, time is a function of the room as the room is a function of the time. Take away one of those, that 'arrow of time' for example, and it won't be 'SpaceTime' anymore. We are constricted around what's called 'constants', the closed doors of 'reality'. One is 'c', another is Plank scale.