If you type for[tab] very fast, it should work and expand your yasnippet. You can set
company-idle-delay to a longer time, like 1 (sec) to have more time for this; the default is quite short at 0.1 sec. If you want the tip and it is not showing, I think you can get it with
If the tip shows, I think you can type C-g to get rid of the hint, then press tab to activate the yasnippet. Alternatively, type
I am not sure you can get it to ignore for otherwise, or if you really want to. What would you do if you wanted completion on something that started with for, e.g. a variable name, other function, etc.?