What should I do if I have just observed minor mathematical typos in my accepted paper? My paper was accepted at a good conference after 3 reviewers cleared it. After proof reading for the publishing, I sent it to the editor with approval. 
However, now I have realised that there are 2 mistakes in the paper: 1. One of the equations dependent on time is using t instead of t+1 2. One of the equations is using best instead of best_i.

The editor has told me that the paper has been sent already for printing, and nothing can be done anymore. Can someone suggest what might be the best course of action now?
As you wrote yourself:


  The editor has told me that the paper has been sent already for printing, and nothing can be done anymore.


Given that the editor decides how a publication runs, there is nothing you can do. "Normal" journals usually publish errata but conference papers often do not have that possibility.

Don't worry about it too much: everybody makes mistakes/typos and it is not a big problem. The intelligent reader will spot the mistakes and not mind too much because he gets the point anyway, the other readers will not spot the mistake so they won't care either. 

Just make sure you learn from this: next time double check everything and ask a meticulous, friendly colleague to do the same.