Two links of a chain connected is a common symbol to use to describe "paired".
Like if you have a bluetooth speaker set paired with your phone, I would expect to see that icon when listing bluetooth devices you have connected to in the past (to indicate that specific device was nearby and you were connected to it), or when scanning for nearby bluetooth devices to indicate which ones you are already paired with, or perhaps as the only icon on a button whose purpose is to pair with the currently selected device.
