a) Look for another statement that comes in pair with this one and utilized by the application in mixed order (no certain order in executing two statements caused by multiple implementation of the same function).
b) If journal_id in the PK for journal_mt and there is a child table referencing it that does not have an index on its FK column.
Both are design problems ( a) is application design problem, b) is database design problem). b) can be a result of missing index as a result of incomplete database migration to a new server or simply deleted by accident.
In case of the second scenario you have another table locked... THE ENTIRE TABLE as a result of this "innocent" query.