Supposedly, there actually are arch-fey in the 4E cosmology on par with archdemons, and it is these who grant you your powers. None are technically statted out, AFAIK, but would presumably be level ~29-33 challenges if the given Demon Lords and lesser deities are any indication. Presumably, by that point you're such a skilled Warlock that you yourself are your power supply, or you're drawing energy from the Feywild itself.

There is a sidebar on page 36 of the 4E Manual of the Planes that spells out some ways a Feylock can gain their abilities, but it's implied that the Fey's reasons for empowering someone are as enigmatic as the Fey themself. Really, I see little difference between the archfey and the things from beyond that grant a Starlock their abilties in the standard flavor, so you can generally think of them as similar.