I might be wrong but I think what you've heard is "ya está." When we Spanish speakers say it, it kind of sounds like "yastá." We usually use it when something is done or ready. It can also be translated as "that's it."

'Ya hasta' dont't have any sense in Spanish. 'Ya basta' meaning 'Is enough' but I'm not sure this expresion was that you earing in Spaing. Where did you were in Spain?

Hola Nichakorn, ya hasta lo utilizamos en frases como por ejemplo: - Mañana me voy de vacaciones y ya hasta agosto no vendré por aquí. (I'm going on holidays tomorrow and I won't be back until August) - Pues es que... yo me marcho ahora y ya, hasta mañana, nada. (The thing is that I'm leaving now, so (there is) nothing (I can do) until tomorrow. You could perfectly remove the "ya", but it's there to specify that it's going to be a long time. We use it specially to mean that other people or other things will have to wait until that moment. - No lo voy a hacer ya hasta mañana (I won't do it until tomorrow) (It will have to wait until tomorrow).