Wrist lock? How do you get this to a lock? For me it's more a wrist/forearm control.. There is no twisting motion on the wrist in gokyo when I do it (I mean it's like ikkyo but with the wrist hand under the wrist, palm up, compared with over the wrist palm down.). Maybe in the end of a knife disarm where one pushes the wrist down to the mat and lift the elbow (kind of chicken-wing like). Is this what you mean?
Gokyo - sometimes called ude nobashi (i.e. arm stretching)