How to check for issues after a power failure?

This morning, the electricity went out for a second, and my computer shut down, then started back up when the power came back on.

How can I be 100% sure that no important Windows files (or the registry or master file table) were corrupted? I'm a bit paranoid because my old computer developed a debilitating (and still undiagnosed) problem in which the hard drive would lock up at random intervals, and that computer turned out to have a corrupted master file table (although that may have been caused by the problem that caused to locking hard drive rather than being the cause). I don't want anything like that happening to this computer.

I've already run chkdsk /r C: in an elevated command prompt. Is there anything else I can do to make extra sure that there's no damage?

I have a very recent (last night) system image backup of Windows made using Macrium Reflect Free, but I think that using it at this point would be an overreaction.

Going forward, consider using an UPS with enough wattage to handle your computer center.
"...I have a very recent (last night) system image backup of Windows made using Macrium Reflect Free, but I think that using it at this point would be an overreaction..." Not an over-reaction at all; I have restored my OS partition several times amongst my three computers over the years due to external and internal problems -- no more worries.

RolandJS said:

Going forward, consider using an UPS with enough wattage to handle your computer center.

I plan to buy one soon. Unfortunately, the power went out before I got it.

"...I have a very recent (last night) system image backup of Windows made using Macrium Reflect Free, but I think that using it at this point would be an overreaction..." Not an over-reaction at all; I have restored my OS partition several times amongst my three computers this year due to external and internal problems -- no more worries.

But what if it wouldn't work right, and I'd be left without a working computer? (I don't have an extra hard drive to test out the restored backup on, so I'd have to overwrite my current hard drive.) I've never restored from a backup before (I've successfully cloned my hard drive using Macrium, but cloning and restoring from an image are a bit different).

Do you think it would be safer than just trying to check for issues on my current hard drive?

The only difference between cloning and restoring from an image is that you get to keep that image and be able to restore from it at any time. All you have to do is to make image of complete disk with all the partitions and a rescue disk/USB to boot and restore from. It also has a bonus of being able to fix eventual BOOT problems and restore image from SATA in IDE mode to a SSD with SATA in AHCI mode.