The advantage of using NaBH3CN is that it isn’t a strong enough reducing agent to reduce aldehydes or ketones, but it is a strong enough nucleophile to reduce iminium ions.
The other option for this reaction is Sodium triacetoxyborohydride (CAS 56553-60-7). Both should selectively reduce the imine in preference to your conjugated ketone. Cyanoborohydride is maybe a bit more selective, but triacetoxyborohydride less toxic.