A microt was a unit of time. One microt was equal to just over second. ("Crackers Don't Matter")
When Aeryn Sun was injured, John Crichton noted that she had four minutes, quickly correcting himself and stating that it was 180 microts, suggesting that a microt was equal to approximately 1.333 Earth seconds. ("The Flax")
It is likely due to a microt being just over a second rather than exactly a second that the term is left untranslated by translator microbes.