It is an illusion created by the non equilibrium state of matter around us. In this universe, a rock hit my head, from our understanding of reality, something happened between the impact and the rebound of the rock. So based on this understanding, time exists only, because of events and interactions of matter. So if nothing existed and by nothing, not even nothing existed, not an empty black space, simple nonexistence, then time cannot proceed as there is nothing to perceive and cause any event in this nothingness. And in this nothingness there is no timeframe from a moment ago to now, as we have nothing.
Now this may confuse you, nothing is different from an empty space. "Nothing at all" cannot be easily comprehended by humans. In an empty box (representing the universe) we can document what happened in this emptiness a second ago to now. But in nothingness, there is no space to time and perceive, there is nothing. But even in an empty universe, it could be possible that time also does not exist there , since there is no one perceiving the equilibruim ( someone noticing it would destroy the static universe as something is happening, namely, a person taking note that nothing is happening).
Without time, matter cannot exist. From our understanding of reality, time is triggered by the events caused by matter, so if a universe would have no time, I can assume it has no matter, but time has happened in an alternate universe as I myself, am saying that this universe has no time at all.