Nico Okarr's appearance in 3631 BBY was identical to how he looked 50 years earlier.
Before 3631 BBY, the smuggler captain known as Nico Okarr came into possession of an old Sith artifact while on Korriban. Okarr hinted in a conversation with the Commander that having this artifact, or using it, helped him slow down the aging process and gave him a kind of extended lifespan. The Outlander noticed that Okarr looked exactly the same during the Galactic War in 3631 BBY as he did many decades before, showing how powerful the artifact was.
Although it was never directly stated, the relic Okarr had may have been one of the items Farel Wickes obtained on Korriban and then traded to Okarr right before the events shown in the Return cinematic trailer. It is suggested that after taking Satele Shan and Jace Malcom to Coruscant after the Battle of Korriban, Okarr got away on his freighter, taking the Sith artifacts he had illegally obtained with him.