old domain vs new domain
 

How much does it make in terms of seo in google? for instance, I have a 6 year old domain which i havent used in ages, but has nothing to do with keyword i want to market, would it be possible to change the anchor on hardlinks to the keyword I want? or would it be better to just buy a new domain closer to keyword?

I've seen sites with weird domains but with different anchors which rank pretty good

It would help a lot if your domain name has the keyword in it. Especially if the domain name is nothing but the keyword.

For example: keyword "stockings"

stockings.com <-- great
sexstockings76841.com <-- not so good

Of course, 6 year old domain would be better for SEO than younger domain name.

Is an old domain without keywords better than new domain with keywords? Maybe. It could be. You just have to test it out, don't you. Otherwise you would not know.