is there any way to read the sd card when phone connected to PC in Mass Storage Mode
No. In mass storage mode the phone effectively acts as a card reader, so the PC has complete control over it. If the phone were to mount the card at the same time as the PC, the filesystem on the card would become corrupted. That's why Android phones don't offer USB mass storage any more.

With MTP, the PC goes through what's effectively a file server on the Android phone, instead of mounting the card's filesystem completely. That way, the phone still has access to the card, and the phone can control what the PC can access.