We found some Android 5.0 Lollipop styled soft navigation keys enabled theme on Play Store viz. eXPERIAnZ Xperia Azuro, Sunset Theme especially for non rooted devices. You need android 4.3+ Xperia device to install the theme or Xperia theme engine enabled ROM.
You get new soft navigation keys from Android 5.0, customized lock screen and home screen wallpaper, themed system UI. It is confirmed working on non rooted Xperia Z1, Z2.
Xperia Azuro Theme
Download eXPERIAnZ Xperia Azuro theme from below.
Xperia Sunset Theme
Download eXPERIAnZ Xperia Sunset theme from below.
Install the above themes on your device and let us know if you like them. Drop your comments below.