Multicast is really sent everywhere on the same LAN. Only hosts that have subscribed to the multicast group will listen to a multicast packet for that group.
Multicast has its own set of destination addresses. For IPv4, the range of multicast MAC addresses is
01:00:5e:7f:ff:ff. There are 28 bits of IPv4 multicast group addresses, but there are only 23 bits of MAC multicast addresses. That means that every multicast MAC address represents 32 different IPv4 multicast addresses (
28 - 23 = 5 and
2^5 = 32). The difference is handled at layer-3.
(IPv6 has a much, much larger multicast address range than IPv4, 120 bits vs. 28 bits, and its MAC multicast address range is
33:33:ff:ff:ff:ff, which is larger than the IPv4 MAC multicast address range, but again there is overlap, and IPv6 multicast has flags and scopes, and it is much more complex than IPv4 multicast.)
At layer-2, the layer-3 multicast address is converted to the MAC multicast addressing for the destination MAC address. A host subscribed to a multicast group will also listen for traffic with the multicast MAC address for the multicast IP address, and it will pass that traffic up to layer-3 to determine if the layer-2 multicast address is indeed for the layer-3 multicast group subscribed to by that host.