cp_fediverse_activities request on database make a very long time
### Describe the bug
We're experiencing sql overload problems on our server due to the `spark tasks:run` task generating those sql query
```Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` ="```
that won't stop (over 900 seconds).
The problem is that this cron job is launched every minute, so the sql requests accumulate and load the server.
## Screenshot or logs
Extract from mytop :
```
100525 pod_uzer localhost castopod 929.5 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100562 pod_uzer localhost castopod 869.3 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100589 pod_uzer localhost castopod 809.6 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100630 pod_uzer localhost castopod 749.7 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100672 pod_uzer localhost castopod 689.9 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100699 pod_uzer localhost castopod 629.7 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100737 pod_uzer localhost castopod 569.8 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100770 pod_uzer localhost castopod 509.4 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100792 pod_uzer localhost castopod 449.9 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100825 pod_uzer localhost castopod 389.8 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100859 pod_uzer localhost castopod 329.7 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100894 pod_uzer localhost castopod 269.8 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100920 pod_uzer localhost castopod 209.6 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
100948 pod_uzer localhost castopod 149.8 0.0 Query Creating sort i SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC
```
Explain on on request :
```
EXPLAIN SELECT * FROM `cp_fediverse_activities` WHERE `scheduled_at` <= UTC_TIMESTAMP() AND `status` = 'queued' ORDER BY `scheduled_at` ASC:
*** row 1 ***
table: cp_fediverse_activities
type: ALL
possible_keys: NULL
key: NULL
key_len: NULL
ref: NULL
rows: 366074
Extra: Using where; Using filesort
```
### Steps to reproduce
1. crontab executed all minutes
2. see request with mytop in mysql
3. clean all request in mysql to unlead the server
### Context
- Castopod: 1.12.3
- OS: DEbian 12
- Browser: all
- Web server: Apache
Best regards
issue