Censys expands queries to provide additional functionality. For example, the query a:zmap.io
executes a DNS lookup and expands to ip:141.212.120.90.
Your query was changed from:
parsed.tbs_noct_fingerprint: 217d09272000b283f64e2fb9e156adf8340ca35357babcaa3cb25b297d4da895 and precert: true
to
parsed.tbs_noct_fingerprint: 217d09272000b283f64e2fb9e156adf8340ca35357babcaa3cb25b297d4da895 AND precert: true
If this isn't what you intended, you can run your raw query without expansion.