Ice melts when heat is transferred away from it to its surroundings. Water is denser than air, so heat is conducted away from the ice faster in water than in air.
Ice will melt fastest in whatever delivers heat to it fastest. In general that will be water because water conducts heat and carries heat better than air. But extremely hot air, such as that from a torch, will beat out very cold water, such as ice water, in melting the ice.