The Holder of the Keys is the chief of servants in the Sun Palace in Cairhien. This official is identified by a ring of heavy silver keys worn at the waist. It's said that no matter who rules Cairhien, the Holder of the Keys rules the Sun Palace. The position was last known to be held by Corgaide Marendevin.
In the Chachin palace, the holder of this position is known as the shatayan. This may have only been a Malkieri word, however, as it was used to describe the holder of the position when al'Lan Mandragoran arrived at the palace.
Reference: New Spring, p 298