Hi Loly,
Congratulations on your new Kelsey! You don’t really need quoins and a key, because Kelsey designed their chases to be used with:
Chase Irons – Two flat steel bars that are placed inside the chase and used to prevent chase screws from damaging furniture (wood blocking). They are not used with quoins. You will need six chase screws also. And some furniture for lock up.
http://www.ebay.com/itm/KELSEY-CHASE-SCREWS-SET-OF-7-COMPLETE-SET-S…
http://www.ebay.com/itm/KELSEY-CHASE-BARS-LETTERPRESS-BARS-FOR-KELS…
If you don’t have them you can order them from the seller above; or if you are handy you could go to the hardware store buy steel bar stock, set screws and an allen wrench for the screws. Bring the chase with you so you can get the correct size set screws.