Bojana, live URLs are not necissarily stored in one place; you need to look though the hierarchy of the content tree to determined the full URL. There are quite a few different settings tha cen effect the URL that is used.
CMS_Document certainly contains alot of the componet parts. A route you can use is to take the
NodeAliasPath from the
CMS-Tree table. This may not take in to account any additional URL settings though.
It's worth asking what you want to use it for, if you'r eplanning to modify it in any way, then changing the
CMS_Document.DocumentUseNamePathForUrlPath would be the way forward. For example:
SET DocumentURLPath = '/awesome-url', DocumentUseNamePathForUrlPath=0
You'll need to flush your cache no doubt after this.