It is unvoiced and is pronounced near the back of the throat -- it's an unvoiced uvular fricative, and actually the symbol is not (or should not be) an x, but a similar character that looks like the Greek letter chi [χ]. The sound doesn't occur in English, so very often it's replaced by [k]. The IPA is basically an agreed system of representing sounds. The problem is that when describing how words are pronounced in different languages, it's not always very easy.
朗文当代里面是有啊,而且是IPA音标,不是KK音标,音标表里给的例词就是loch
有的词典里loch的最后一个音标是/ k /
我还查了商务印书馆的朗文当代大辞典,是/ x /
但/ x / 这个音标不多见,并不是所有的用/ k /的词都用/ x / ,就是说朗文当代里面既有/ k /,也有/ x /