An Ancient Key is a Guardian object obtained by scanning the data core of a reactivated Guardian Beacon. It is a legal salvage item.
A crystal found by scanning the data core of a Guardian Beacon. It appears to contain a similar ethereal type of energy as the Ancient Relics found at the ruin sites of the Guardian civilisation. Like the relic this item is used in Guardian technologies, unlocking new data and functions. Hence it has been given the designation of "Key".
— In-game description