Can mp3 song be played in a keyboard with usb?
If such a thing is possible, it will be described in the keyboard manual.
Generally, no. USB on a keyboard is usually for a MIDI emulation, to send keypresses to a program on a PC. Some keyboard may also have a facility to load audio samples, but they may be limited duration and not an entire song - but there are thousands of different makes and models, all with different capabilities.
Try it. If it DOES have a usb outlet... it's probably to stream the keyboard music out onto the tv thru audio.