In what way does it look like a perfect? Perfect tense is marked by a specific set of personal endings; ἥκω uses the same thematic endings as the present tense. Just because it has a kappa doesn't mean it's a perfect (there's no rule that a stem can't end in a kappa, furthermore, not all perfects are indicated this way).
IPHIGENIE: Kann uns zum Vaterland die Fremde werden?
ARKAS: Und dir ist fremd das Vaterland geworden.
IPHIGENIE: Das ist's, warum mein blutend Herz nicht heilt.
(Goethe, Iphigenie auf Tauris)