ESP 32 Receiving HTTP Response code: 200 but nothing is inserted to database table

Did you run the curl command in the same network environment?

do you see any text returned from the curl command?

can you try with

if (WiFi.status() == WL_CONNECTED) {
  WiFiClientSecure client;
  client.setInsecure();
  HTTPClient http;

  String url = "https://iotgassensory.com/post-data.php";
  String payload = "api_key=" + apiKey +  "&value1=27.88&value2=9.45&value3=1004.7";
  http.begin(client, url);
  http.addHeader("Content-Type", "application/x-www-form-urlencoded");
  int httpResponseCode = http.POST(payload);

  if (httpResponseCode > 0) {
    Serial.print("HTTP Response code: ");
    Serial.println(httpResponseCode);
    String response = http.getString();
    Serial.println(response);
  } else {
    Serial.print("Error code: ");
    Serial.println(httpResponseCode);
  }

  http.end();
}