You're two adults and two kids - just take charge of one each. I flew alone a lot with my 3 when they were all under 5 and it is very doable as long as you plan and pack (hand luggage) sensibly.
The 3 year old takes his or her own tiny rucksack with a sparing change of clothes (shorts, pants, t-shirt) and some small toys.
Each parent packs a similarly small folding emergency change of clothes for themselves (in case the child pees/ nappy leaks/ smears food or snot/ throws up or spills something on you) and the adult in charge of the one year old also carries two nappies, nappy bag, wipes and a change for the one year old.
Each parent carries extra wipes plus some surprises to distract the child they're in charge of (tiny new book, colouring book and crayons not felt tips or better if you can get one a "paint with water" colour change book), a couple of new Playmobil 1-2-3 figures (nothing complex nor with wheels), and lots of single portion varied "clean" (as in nothing that melts like chocolate) snacks. Buy drinks after security or take empty water bottles to fill. Obviously if the youngest uses a dummy take 7 just in case, and if there's an indispensable cuddly toy or blanket take your secret duplicate hidden in your spare clothes.
Don't stress, with 1:1 adult to child its easy if you don't get flustered.
Perhaps sit separately, one parent with each child, if one winds the other up or if they're both likely to look to you for everything (or if your husband is the type to fein helplessness or watch his phone and ignore his child if you're there to deal with both).
Which reminds me don't be ashamed to use screens on the flight, without sounds or with headphones for the older one. Flights aren't the place for performing idealised parenting to impress strangers nor for being too idealistic yourself - it's all about keeping everyone quietly content and relatively clean/ unsticky 🤣