Mysql fast rand order search

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random

we have a table of 50k items and we display it at search page with random sort and 10 items per page , and there is some filters
random with/without seed is very slow
note that items are 3 category and first category should be display first with random order , then the second category with random order also

- generate random number between 0 and max id will is not working because of pages and the previous constrains
- randomize the records with php make items always display at the same page

any better solution to speed up search?