Mascarita Sagrada 2000 is the current champion. Sagrada won the championship on November 5, 2004 in Veracruz while a member of AAA. In fall of 2007, Sagrada jumped to CMLL while still champion. He's now wrestling as Mascarita Dorada, and this championship has not made an official appearance yet. Sagrada/Dorada clearly still should be champion - one of the key reasons for his promotion switch was AAA booking a match where he'd lose it to Mini Histeria.
This championships has occasionally been mentioned by commentators during Mascarita Dorada's matches, but the belt has rarely (or maybe never) been shown in CMLL. When CMLL decided to put a secondary minis championship in play, they opted to use the Mexican National Lightweight Championship instead of more logically using this one.
It's was assumed that Sagrada/Dorada had physical possession of the belt, but a source says AAA may actually still have the actual belt, and that's why Sagrada/Dorada hasn't defended it since leaving AAA. Regardless, the championship itself remains in limbo and looks to remain there for a long time. Dorada is unlikely to return to AAA any time soon, AAA is unlikely to give him the belt if they have it, and there's no third party strong or interested enough to force a conclusion.