Imma Tell Absolute Power Tech N9ne

catchin' keys from across seas

Bill is right, though this is a quote from Wu-tang-C.R.E.A.M..It means that they are buying Kilograms of narcotics that are imported.
this could mean he's on the receiving end of drug shipments (in quantities of kilograms/kilos/keys) being imported into the united states from south american or asian countries
catchin' refers to obtaining ... keys refer to "keys to a house" ... across seas mean in another country. "I am buying houses in other countries" i.e. being rich and having several houses all over the world~