Go でレコードの存在を効率的に確認し、存在しない場合は挿入する方法

package main

import (
    "database/sql"
    "fmt"
    "os"

    "github.com/gin-gonic/gin"
)

func main() {
    router := gin.New()
    router.Use(gin.Logger())
    router.Use(gin.Recovery())
    dbUser := os.Getenv("DB_USER")
    dbPwd := os.Getenv("DB_PASSWORD")
    dbHost := os.Getenv("DB_HOST")
    dbPort := os.Getenv("DB_PORT")
    dbDatabase := os.Getenv("DB_NAME")
    db, err := sql.Open("mysql", fmt.Sprintf("%s:%s@tcp(%s:%s)/%s", dbUser, dbPwd, dbHost, dbPort, dbDatabase))
    if err != nil {
        fmt.Print(err.Error())
    }
    err = db.Ping()
    if err != nil {
        fmt.Print(err.Error())
    }

    var exists bool
    query := "SELECT EXISTS(SELECT 1 FROM ...)"
    row := db.QueryRow(query)
    if err = row.Scan(&exists); err != nil {
        return err
    }

    if !exists {
        query = "INSERT ...";
        if _, err = db.Exec(query); err != nil {
            return err
        }
    }
}