Aghadowey does it again with that will, the townland made me focus Ballynacooley Toome County Antrim which is in Duneane civil parish 
I stopped before 1901 census so no Cargin entries but you should find an earlier relative or something of interest griffiths valuation has continuation books online at PRONI
1796 Flax growers of co antrim none found
1823-1837  Tithes Applotment Books based upon the index work of the Irish Genealogy Hub      The relevant original books are in the 
Public Record Office of Northern Ireland (PRONI) Belfast
Keyland, John-Townland:       Lurgill Year: 1833-      Ballinderry -Antrim
Keylan, Wm.-Townland:       Ballynacooley Year: 1833-Duneane-Antrim
Keylan, Wm.-Townland:       Killyfadd Year: 1834-   Drummaul -Antrim
Keyland, James-Townland:       Aghadolgan Year: 1834-   Glenavy-Antrim
Keyland, James-Townland:       Aughadalgan Year: 1826-   Glenavy-Antrim
Keyland, John-Townland:       Aghadalgon Year: 1826-   Glenavy-Antrim
Keyland, John-Townland:       Aghadolgan Year: 1834-   Glenavy-Antrim
Keyland, Chas.-Townland:       Ballyvannan Year: 1826-   Glenavy-Antrim
Keyland, Daniel-Townland:       Ballyvorally Year: 1826-   Glenavy-Antrim
Keyland, Daniel-Townland:       Ballyvorally Year: 1834-   Glenavy-Antrim
1860ish         Griffiths Valuation of Ireland with thanks to 
http://www.askaboutireland.ie/griffith-valuation/ for detail and map ref use 
http://www.askaboutireland.ie/griffith-valuation/Surname   First Name   Townland   Parish   County sorted by parish then by townland
Keyland   Maria      Clonboy   Drummaul   Antrim
Keyland   Daniel      Aghadolgan   Glenavy   Antrim
Keyland   James      Aghadolgan   Glenavy   Antrim
Keyland   Maria      Aghadolgan   Glenavy   Antrim
Keyland   William   Aghadolgan   Glenavy   Antrim
Keyland   Charles   Ballymacricket   Glenavy   Antrim
Keyland   Maria      Ballymacricket   Glenavy   Antrim
Keyland   Daniel      Ballyvorally   Glenavy   Antrim
Keyland   William   Ballyvorally   Glenavy   Antrim
Keyland   Daniel      Edenturcher   Glenavy   Antrim
however I turned up the occupants list and said the name out loud and think this is the best clue for me to follow up
KILLEEN   JAMES   ANTRIM   DUNEANE   1862 map ref 7a 7 acresabove railway line
KILLEEN   JAMES   ANTRIM   DUNEANE map ref 7b 25 acres   the house valued at £2 five shillings  is the best in the townland. looking up their map ref tells me its just south of old railway line and its drive exists on modern maps there are two entries  driveway the first house is modern and closeto the road I guess its no 2 Ballynacooley Rd the older one is Unnamed Road Antrim BT41 3NA54.707428, -6.386330 but numbered 4 Ballynacooley Rd and I see white pebbled dash cottage at top of drive   is it the old family Keyland /Killeen homestead 
KILLEEN   JAMES   ANTRIM   DUNEANE map ref c 2 above railwy line
Ballynacooley
but why so few in census 1901, is it employment in Belfast ot have they all emigrated 2 did from Belfast port james aged 40 and john aged 26 but doesn’t say from a location 28 aug 1849 which could be the famine see 
http://www.castlegarden.org/search_02.php?m_ship=&po_port=&p_first_name=&p_last_name=keyland&o_occ=&co_country=&province=&town=&m_arr_date_start=1820&m_arr_date_end=1913&submit.x=63&submit.y=2other sources
https://www.GenesReunited.co.uk/tree/results/keyland?memberkey=0&yearofbirthrange=0&birthplace=irelandthe chief tree owner for Co Antrim Keyland is “ella” followed by Kathleen,,june godfrey Roy,Debbie , there are 25 entries. earliest entry is  
Mary   Keyland   1752   Co Antrim N Ireland ...    
No Keylands found
you would probably have to join to ask permission to see the trees others have. 
however currently on line are 60 brief entries for keyland at
https://www.ancestryireland.com/search-irish-genealogy-databases/?search1=&search2=keyland&submit=Search+All  births 22 earliest1830 but they give fathers names so you can try to make trees yourself
marriages 34 earliest 1840, some fathers names used
also familysearh.org and emerald ancestors
PRONI lookup their Wills among there many otherdata base  
GOODLUCK ONWARDS