This is an odd one. It does appear to be a corrupted database of some sort.
The SQL statement that is trying to run when it times out is:
UPDATE `tbl_product` SET `module` = 'product', `title` = 'Stratus Spinner, Blue', `subtitle` = '', `sku` = 'HH127', `intro` = '', `detail` = '', `category_id` = '', `subcategory_id` = '', `display_id` = '3', `image` = '', `sort` = '', `publish` = '1', `dateinsert` = '2019-01-04 00:00:00', `dateupdate` = '2020-04-10 00:00:00', `slug` = '', `featured` = '', `new` = '1', `outofstock` = '1', `limitedstock` = '', `artgroup` = '', `relatedonly` = '', `keywords` = '', `datestart` = NULL, `datestop` = NULL, `author` = '', `file` = '', `link` = '', `videoembed` = ' ', `weight` = '0.00', `price` = '69.00', `percent` = '10', `priceeach` = '0.00', `preprice` = '0.00', `filetype` = '', `prodsize` = '89.5"h x 19"w x 19"d', `relatedid` = '', `detail1` = '', `detail2` = '', `detail3` = '', `detail4` = '', `detail5` = '', `minimum` = '2', `case` = '1', `comingsoon` = '', `comingwhen` = '' WHERE `id`='1514'
It is a simple one row update, so it shouldn't cause an issue. I also tried running:
REPAIR TABLE tbl_product
That also times out with a 500 error.
Maybe try running the repair from phpMyAdmin. I'll try a few more things, but it looks like the database itself is the issue here.