You can encrypt & decrypt a string using AES_ENCRYPT & AES_DECRYPT.
INSERT INTO TABLE-NAME (`column1`,`column2`)
VALUES(AES_ENCRYPT('value1','key-xyz'),AES_ENCRYPT('value2','key-xyz'));
SELECT AES_DECRYPT(column1,'key-xyz') AS column1,
AES_DECRYPT(column2,'key-xyz') AS column2 FROM TABLE-NAME
UPDATE TABLE-NAME SET `column1`=AES_ENCRYPT('value1','key-xyz')
WHERE AES_DECRYPT(column2,'key-xyz')='value3'