Thank you for you support.
Shared web hosting doesn't allow that. I tried to contact the host support via chat, they don't reply due to corona virus problem. I'm sure if they replied they will say check your script. I have online statistics add-on, before moments the error happened again while there were only 3 users online, 10 users visited the shop in that hour, 79 page view . I downloaded the site log, there is no suspicious visits. What do you think the cause of that error (.. exceeded the 'max_questions')? I have these installed add-ons.
Is there something related to Open Cart can I do, like disabling features that consumes a lot of quires.?
What I must ask about when choosing a VPS for a website that have a maximum of 200 users per day? the shop has about 1500 products.