Android app to circuit trigger
I'll recommend you to use ESP8266 ,especially ESP-12E for such wifi based controlling. It costs only ~$5. All you need to do is ,learn the esp to program(preferably Arduino), Connect to wifi network broadcasted by the esp chip and you're done for connection part. The ESP-12E have lot of peripherals like GPIO ,from which you can switch relay( buy a 3.3v relay switch), I2C , SPI so on. For Android app, you don't necessary need it. You can control it with your webpage itself by programming the chip appropriately. If you want a android app, try to create an app by your own. There are lot of free tools available for creating android app, and it'll take less time to create such app. For unlocking door, you can use a servo motor. Nevertheless , try not to use the door unlocking your main door of home. Chances that a hackers may hack for the WiFi password and they access to your home. So try the door unlocking for your small rooms inside your home itself. The most critical part you need is ESP-12E itself. For door unlocking/locking ,you need a servo motor which you need to connect to the door in such a way that ,when it rotates 90 degree, it unlocks and after 30 sec(say) it'll automatically lock and Arduino IDE with ESP library installed(get it from GitHub).For controlling, you need at least a web browser with wifi connection(it can be a laptop, phone) or android phone ,with app created by you (refer google for easy way to do apps) and add stuffs like power supply etc., by yourself