When any substance is subjected to heat of any kind of energy, they enter their excited state and vibrate with greater amplitude.
This allows more collisions between atoms which means faster reaction.
Theoretically, its assumed that at 0K (-273.15°C) there is no kinetic energy in the atoms and hence, no reactions taking place :)
Because when the atoms are warm or hot they have sufficient or we can say extra energy and they vibrate to use that energy. But vibrating is not just enough so they also react with other atoms to somehow reduce the amount of that extra energy.