I have problem with interrupt on 16f690
Your template is faulty a little bit . You have to wait anywhere until overflow a interrupt.

Please try Below template that I edited version.

void main()   
{   
    OPTION_REG=0x80;  
    ANSEL=0x00;
    ANSELH=0x00; 
    CM1CON0=0x00;        
    CM2CON0=0x00; 
    T1CON=0x00;
    TRISA=0b00000011; PORTA=0x00;
    TRISB=0b00111111; PORTB=0xff; 
    TRISC=0x00; PORTC=0x40;
    INTCON.RBIF = 0; // Clear interrupt flag prior to enable  
    INTCON.RBIE= 1; // enable on change interrupts  
    INTCON.GIE = 1; // enable Global interrupts 
    while(1){__delay_us(1)} 
}


void interrupt isr(void)  
{ 
   if ( INTCON.RBIF==1)  
   { 
      LED^=1; //Invert for test.
      INTCON.RBIF = 0; 
   }
}