The letters X and Y are printed on the PCB next to the chip
Considering the way that those letters are oriented, along with that style of IC package, then this IC is probably an accelerometer.
Looking at this cropped version of the original photo, I've marked the "Y" and (I think) the "X" which you mentioned:
The letter "X" is at the 3 o'clock position, indicating that the X-axis is in an east-west plane. Similarly, the letter "Y" is at the 12 o'clock position, indicating that the Y-axis is in a north-south plane. (The Z-axis would therefore be the plane "in and out of the screen".)
In an electronic lock, an accelerometer could be used to detect tampering e.g the lock being removed from the door (change of orientation, while the lock is set), or the shock from external attempts to force the door.
Update: I just looked on a product page for your Schlage BE469 lock, which refers to a "built-in alarm" feature. For example, the lock's user guide refers to a "Tamper" setting (page 8), which "Alarms when the lock is disturbed". A classic use for an accelerometer in modern consumer electronics is detecting the mechanical shock when someone attempts to tamper with a device, so that helps to confirm that the lock does likely contain an accelerometer.
Therefore I suggest to focus the search for an accelerometer as that IC, if you want to identify a specific device.
(On a side note, from the amount of apparent flux that's visible around it, someone might have tried to replace that IC already.)