documentclass[ngerman,twoside=false,listof=totoc,listof=leveldown]{scrbook}
usepackage{imakeidx}
usepackage[style=archaeologie]{biblatex}
addbibresource{archaeologie-examples.bib}
usepackage{babel}
newcommandtocgobble[1]{}% <- added
newcommandtocpageseparator{footnotesize,mbox{---},}
newcommandtocpagenumberbox[1]{mbox{#1}}
KOMAoptions{toc=indentunnumbered}%indent only for section* !?

RedeclareSectionCommands[
  tocraggedpagenumber,
  toclinefill=tocpageseparator,
  tocindent=0em,
  tocnumwidth=4em,
  tocpagenumberbox=tocpagenumberbox
]{chapter,section,subsection,subsubsection,paragraph}

RedeclareSectionCommand[
  tocentryformat=largescshape,
  tocindent=0em,
  tocnumwidth=4em,
  tocpagenumberbox=tocgobble
]{part}

RedeclareSectionCommand[%
  tocentryformat=textbf%
]{chapter}

makeindex[
  intoc,
  name=loc,
  title={Locations},
  columns=3,
  ]
indexsetup{%
  level=section*,
  toclevel=section,
  noclearpage,
  firstpagestyle=scrheadings,
  headers={indexname}{indexname},
    }
begin{document}
  nocite{*}
  frontmatter
  tableofcontents
  mainmatter
  part{part}
  chapter{chapter chapter}
  section{section section section}  section{section section section}  section{section section section}
  part{part}
  chapter{chapter chapter}
  section{section section section}  section{section section section}  section{section section section}
  setcounter{page}{100}
  part{part}
  chapter{chapter chapter}
  section{section section section}  section{section section section}  section{section section section}
  backmatter

  part{part}
index[loc]{A location}
  chapter*{Abbildungs-, Tabellen-, Tafelverzeichnis}
  addcontentsline{toc}{chapter}{Abbildungs-, Tabellen-, Tafelverzeichnis}
  listoffigures
  chapter*{bibname}
  addcontentsline{toc}{chapter}{bibname}
  printbiblist[%
      heading=subbibintoc,%
    title={Zeitschriftenabkürzungen}]{shortjournal}
  printbiblist[%
    heading=subbibintoc,%
    title={Reihenabkürzungen}]{shortseries}
  printbibliography[heading=subbibintoc]
chapter*{Indizes}
addcontentsline{toc}{chapter}{Indizes}
printindex[loc]
end{document}

documentclass[ngerman,twoside=false,listof=totoc,listof=leveldown]{scrbook}
KOMAoptions{toc=indentunnumbered}%indent only for section* !? % No
begin{document}
  tableofcontents
chapter{Wombat}
section{Wombat}
addchap{Capybara}
addsec{Carl}
chapter*{Lion}
addcontentsline{toc}{chapter}{Lion}% Not the KOMA way
section*{Laura}
addcontentsline{toc}{section}{Laura}% Not the KOMA way
end{document}