Quick thought, it may be worth looking into splitting the table in two, one for the "Tasks" and another for the "Process attempts", so instead of updating the column a new row is added to the latter table. This kind of "flag" update is a very common cause for blocking on a busy system.

😎

+-----------+ +--------------+

| TASK | | PROCESSED |

+-----------+ +--------------+

| TASK_ID |-+--, | PROCESSED_ID |

| <details> | '-----0<| TASK_ID |

+-----------+ | <details> |

+--------------+