Performing planks, side planks, crunches and/or Russian twists (or whatever your core training might look like for golf) can certainly improve your core stability and/or core strength. Common swing faults if you have poor core stability can include loss of posture and reverse spine angle.
However, how well will these transfer to your golf swing?
Performing core stability exercise wont help you during your golf swing if the segments above and below the core do not function properly. That is, if the hips and thoracic spine are not mobile.
E.G. If you lack thoracic rotation, you will still attempt to compensate, and gain extra rotation or create that reverse spine angle to achieve a full backswing through moving from the low back (just when you have been training to stay more stable), you can increase your risk of low back pain/injury.
Therefore, working on your core stability to keep your low back more stable during the golf swing and to reduce your low back pain wont help much. You need to take a player focused and whole body approach.
You need to look at hip mobility and thoracic mobility. Chances are that the low back will compensate for a lack of mobility in one of these areas.
Therefore, alongside your core stability exercises, and more important than core stability for reducing low back pain in golfers is to improve hip and thoracic spine mobility.
Click the links below for videos to show you how to improve your thoracic and hip mobility.