Here's the direct information: Current version: SKSE 2.2.3 (runtime 1.6.640)
I understand you're looking for the version for Skyrim SE 1.6.640 , along with a "feature" explanation.
You can download it from the official site: skse.silverlock.org
Cookie Info
The cookie settings on this website are set to 'allow all cookies' to give you the very best experience.
If you continue without changing these settings, you consent to this. If you want, you can change your settings
at any time by visiting our cookies page. skse for 1.6.640