Please post DDL, so that people do not have to guess what the keys,
constraints, Declarative Referential Integrity, datatypes, etc. in your
schema are. Sample data is also a good idea, along with clear
specifications. Even pseudo-DDL is better than narratives. Is this
what you meant?

CREATE TABLE Foobar
(event_time DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL,
user_name VARCHAR(16) NOT NULL,
stuff_1 INTEGER NOT NULL,
stuff_2 INTEGER NOT NULL,
..
stuff_n INTEGER NOT NULL,
PRIMARY KEY (user_name, event_time));

SELECT F1.*
FROM Foobar AS F1
WHERE F1.event_time
= (SELECT MAX(f2.event_time)
FROM Foobar AS F2
WHERE F1.user_name = F2.user_name);
-- use column names in production code, not SELECT *.