Apart from using boolean operators on the top search bar, you can do querying by using special parameters on the URL of your sheet.
For the sheet
https://www.ragic.com/accountname/tabname/3
You can use
https://www.ragic.com/accountname/tabname/3?pqv100003=New
The part before ? is your sheet path.
The parameter name is pqv
(Your field ID can be found with this method.)
The value after = is the value to filter with, which is "New" in our example above. Please note that this value is case-sensitive.
For multiple queries, you can use the ampersand symbol &.
Comparison operators such as, <, >, or >= will not work with this method. If you need to do this type of comparison, you can use the left sidebar to filter your data.