如何获取Lua中哈希表中的键数？

local my_table = {
    key1 = "value1",
    key2 = "value2",
    key3 = "value3"
}

local key_count = 0

for _ in pairs(my_table) do
    key_count = key_count + 1
end

print("The number of keys in the table is: " .. key_count)