I’ve worked at State Bank of India for six years as a forex assistant—what are my chances of getting a banking job in Europe?

Pretty low. There are enough forex traders in Europe, sometimes more traders than jobs. Besides, your RBI knowledge is of no use to the Europeans. They need you to understand the ECB and EU laws along with European experience to really offer you a job. Unless, you've been a stellar trader (for which you would have been found already).

Bluntly speaking, you don't offer much to them to hire you from all the way from India.