The headword phrase is attributed to Attic comedy (Adespota fr.807 Kock, 509 K.-A.) but may not be correctly quoted here. Other lexica -- see the references at Photius kappa625 Theodoridis -- simply have Keskos as the headword and seem to speak, as here, of 'not having' (ou)k e)/xein) it, which Erasmus and Meineke wished to emend to oi)kei=n ('inhabited').
For paroemiographers see e.g. Zenobius 4.51.
A city called Kestos and a river called Anous -- or, in Photius, Nous -- are not otherwise attested for Cilicia (or indeed anywhere else); probably the names are adapted, deliberately or otherwise, from Kestos and the nearby river Selinous (Barrington Atlas Map 66 grid A4).