How to tell whether email seeking paid peer-reviewers for grant scheme is legitimate? How to respond?
This is most likely genuine, in particular if the proposal to be reviewed fall broadly into your area.

Just check the actual web address of the links given (rather than what they say they are) and/or search the respective institutions online. I did once a similar job for the Polish science foundation.

Actually, if you click the link http://www.ncste.kz/en provided, you will learn that they are attempting to boost their science standing and one way to do that is to get international reviewers.

Don't be too paranoid about viruses, just don't do stupid things (like typing your password into some unknown/new website), or opening mail attachments of unknown origin, etc..