Yes, it really looks like JSON.

Try this:

use strict;
use warnings;
use JSON;
use Data::Dumper;
 
my $json      = JSON->new->allow_nonref;
my $json_text = do { local $/; <DATA> };     #read DATA Block
my $ref       = $json->decode( $json_text ); #get Perl Data Structure
my %data      = %{$ref->{data}->[0]};        #giving the shortcut a na
+me

my %buyQuantity = map {
    $_ =~ m/buyQuantity/ ? ($_, $data{$_}) : () 
} keys %data; # extract data you are looking for

print Dumper(\%buyQuantity); #observe results

__DATA__
{"futLink":"\/live_market\/dynaContent\/live_watch\/get_quote\/GetQuot
+eFO.jsp?underlying=SHREECEM&instrument=FUTSTK&expiry=28DEC2017&type=-
+&strike=-","otherSeries":["EQ"],"lastUpdateTime":"15-DEC-2017 14:55:5
+3","tradedDate":"15DEC2017","data":[{"extremeLossMargin":"5.00","cm_f
+fm":"21,823.45","bcStartDate":"25-JUL-17","change":"-146.90","buyQuan
+tity3":"3","sellPrice1":"17,751.40","buyQuantity4":"5","sellPrice2":"
+17,758.50","priceBand":"No Band","buyQuantity1":"3","deliveryQuantity
+":"93,925","buyQuantity2":"2","sellPrice5":"17,775.00","quantityTrade
+d":"1,09,030","buyQuantity5":"2","sellPrice3":"17,772.10","sellPrice4
+":"17,772.15","open":"18,044.00","low52":"13,140.30","securityVar":"5
+.21","marketType":"N","pricebandupper":"19,688.10","totalTradedValue"
+:"2,741.00","faceValue":"10.00","ndStartDate":"-","previousClose":"17
+,898.30","symbol":"SHREECEM","varMargin":"7.50","lastPrice":"17,751.4
+0","pChange":"-0.82","adhocMargin":"-","companyName":"Shree Cements L
+imited","averagePrice":"17,850.84","secDate":"14DEC2017","series":"EQ
+","isinCode":"INE070A01015","surv_indicator":"-","indexVar":"-","pric
+ebandlower":"16,108.50","totalBuyQuantity":"7,050","high52":"20,538.0
+0","purpose":"DIVIDEND - RS 24 PER SHARE","cm_adj_low_dt":"23-DEC-16"
+,"closePrice":"0.00","isExDateFlag":false,"recordDate":"-","cm_adj_hi
+gh_dt":"15-MAY-17","totalSellQuantity":"7,255","dayHigh":"18,197.90",
+"exDate":"21-JUL-17","sellQuantity5":"1","bcEndDate":"31-JUL-17","css
+_status_desc":"Listed","ndEndDate":"-","sellQuantity2":"1","sellQuant
+ity1":"1","buyPrice1":"17,750.25","sellQuantity4":"2","buyPrice2":"17
+,750.20","sellQuantity3":"2","applicableMargin":"12.50","buyPrice4":"
+17,750.00","buyPrice3":"17,750.10","buyPrice5":"17,735.05","dayLow":"
+17,701.00","deliveryToTradedQuantity":"86.15","basePrice":"17,898.30"
+,"totalTradedVolume":"15,355"}],"optLink":"\/marketinfo\/sym_map\/sym
+bolMapping.jsp?symbol=SHREECEM&instrument=-&date=-&segmentLink=17&sym
+bolCount=2"}
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