{"type":"4","Record channels HDCVI":{"1":"4","3":"16"},
"Supported standarts HDCVI DVR":{"0":"HDCVI","2":"IP","3":"AHD","4":"Analog"},
"Record resolution HDCVI DVR":{"1":"FullHD 1080p"},
"HDD amount":{"1":"2","2":"4"},
"Specs HDCVI DVR":{"0":"2x HDMI","1":"TV-out","2":"Videoanalytics","3":"eSATA","5":"RS-485"}}

"Record channels HDCVI":{" ... :"4" ... "}

/Record channels HDCVI.+"4"}/g

SELECT * WHERE field REGEXP '"Record channels HDCVI":{[^}]*"4"';

{     -- match the opening brace
[^}]* -- match 0 or more characters that are not a closing brace
"4"   -- match literal "4"