Is there a way in drupal 7 translate interface to search for exact keyword? The problem is that when I search for keyword 'no' it gives me 19 pages of results.
No, there isn't any way to do that through admin interface. The string search is based on the LIKE condition which includes hardcoded placeholders (%) to search for all strings containing your provided string.
Only way for you is to directly tamper with the database or go through all 19 result pages.
Alternatively, you could change the code temporary. For that you have to open locale.inc and go to
function _locale_translate_seek() in line 1833. Depending on your search (all, untranslated, translated) you have to look for
->condition('s.source', '%' . db_like($query['string']) . '%', 'LIKE');
and change it to
->condition('s.source', db_like($query['string']), 'LIKE');.
Your search should then only result in exact strings.