The shape is a key - a horizontal line, rounded on the left and pointy on the right with a rough edge on the bottom.
Lock is a common feature on ovens. It disables the buttons to prevent accidental activation. Originally the lock tactile icon was a square shape with an up-side-down hook at the top - similar to the visual icon used on the appliances. The hook was difficult because of the tradeoff between detail and adhesion. And though tactile icon shape to function associations are sometimes a reach, I felt this one required too many brain cells. Perhaps there is something better. A key is used for locking/unlocking so there is an association. Also this key shape has many helpful tactile features - horizontal line, round end, pointy end, rough bottom. Tactile exploration gives a more complete picture of a key.