From GameWatcher: “Each faction in The Division 2 has special loot boxes scattered around the world, each of them requiring a faction key to open. Being the first enemies you encounter in the game, Hyenas boxes come into play relatively early due to their locations around the starting area and the Grand Washington Hotel mission, so the main question is: Where Do you find The Division 2 Hyenas Keys?”
Source: N4G PC The Division 2 Hyenas Key Locations – Where Do you find Hyenas Keys?