\contentsline {lecture}{Lecture\,1\,(date)}{1}%
\vspace \smallskipamount \hspace {1.5em}\parbox {\dimexpr \textwidth -1.55em- 2em}{Some keywords}
\contentsline {lecture}{Lecture\,2\,(date)}{2}%
\vspace \smallskipamount \hspace {1.5em}\parbox {\dimexpr \textwidth -1.55em- 2em}{Some other keywords}