Yes, it is possible to upload product details directly into mysql database but eStore doesn't have any build in function for this yet.
There are a few different ways to do this... you could write a PHP script that opens your data file (excel file), break it up into an array of lines that each represent a row of data, split each line up by the delimiter character (such as a comma ',', tab '\t', semicolon ';', space ' ', etc.), and then perform invididual MySQL INSERT queries (one INSERT for each line) to insert all your data from the file into the appropriate table fields.