First, read your text file, and convert your keys to a comma separated list of items, surrounded by quote characters:
Then, create your SQL query as normal, using an IN clause and the string you made earlier:
SELECT * FROM myTable WHERE key IN ('AA5GTS','JK2UTD')
Execute your query, probably with a DataTable and a DataAdapter but basically with whatever you are used to using.
The data can then be presented as necessary.