>>/34941/
I am incapable of saving even myself. Only rare pics, until my hard drives overflow. We live in hell. Strafplanet Erde, etc.

Anyways, while looking up this pic from MD5 hash recorded by Endchan, I had an idea how to deal with 4chan timestamp filenames in case original MD5 becomes inaccessible, e.g. when you save an image after it was posted here or elsewhere - filename remains original, but MD5 hash does not due to some server-side metadata stripping or compression or whatever.

Poking around I found that desuarchive (and most likely other Fuuka archives) understands time in ISO-8601 format with precision up to seconds, any of the following variants entered into Date start / Date end search fields are valid:
2019-10-13T14:05:31+04:00
2019-10-13 14:05:31+04:00
2019-10-13T10:05:31
2019-10-13 10:05:31
Offset can be anything:
2019-10-13 15:05:31+05:00
It's not evident from legend which only suggests YYYY-MM-DD with no indication that more precise times could be specified.

The following bash function:
fourchan_time(){
for FILE_PATH in "$@";do
	FILENAME=$(basename "$FILE_PATH")
	CHAN4_TS="${FILENAME%%.*}"
	UNIX_TS="$(("$CHAN4_TS"/1000))"
	POST_TIME="$(date --utc --date @"$UNIX_TS")"
	POST_TIME="$(date --utc --date "$POST_TIME 4 hours ago" +'%Y-%m-%dT%H:%M:%S')"
	echo "File: $FILENAME"
	echo "4chan time: $POST_TIME"
	echo "https://desuarchive.org/_/search/filter/text/start/"$POST_TIME"/end/"$POST_TIME"/order/asc"
done
}
Produces search query URL for posts with images in the exact second the target file was posted.
$ fourchan_time 1570975531526.jpg
File: 1570975531526.jpg
4chan time: 2019-10-13T10:05:31
">https://desuarchive.org/_/search/filter/text/start/2019-10-13T10:05:31/end/2019-10-13T10:05:31/order/asc

It's too damn late in the night for me to understand timezones, where to add and where to subsctract, but guess I got it correctly, EST or whatever 4chan uses, 4 hours behind UTC in which archives show their posts. Good night.