edit your file  :

/oxide/data/ServerRewards/reward_data.json

For each item, you can change the cooldown, wich is the last variable of item's array.
On the following exemple, cooldown is 1 second.
60 for a minut, 3600 for an hour, etc.

{
  "items": {
    "lock.code_0": {
      "shortname": "lock.code",
      "customIcon": null,
      "amount": 1,
      "skinId": 0,
      "isBp": false,
      "category": 2,
      "displayName": "Code Lock",
      "cost": 50,
      "cooldown": 1
    },

SeanRon

edit your file  :

/oxide/data/ServerRewards/reward_data.json

For each item, you can change the cooldown, wich is the last variable of item's array.
On the following exemple, cooldown is 1 second.
60 for a minut, 3600 for an hour, etc.

{
  "items": {
    "lock.code_0": {
      "shortname": "lock.code",
      "customIcon": null,
      "amount": 1,
      "skinId": 0,
      "isBp": false,
      "category": 2,
      "displayName": "Code Lock",
      "cost": 50,
      "cooldown": 1
    },

Awesome thanks! For some reason, my file doesn't list cooldown.  Doesn't look like I'm missing anything else.

    "shotgun.double_0": {
      "shortname": "shotgun.double",
      "displayName": "Double Barrel Shotgun",
      "customIcon": null,
      "amount": 1,
      "cost": 5,
      "skinId": 0,
      "isBp": true,
      "category": 1
    },