SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd77e40b337a57c00f5f04817d91f2e651ea85a9638370779376f0c4e5a3b16ff' 
  AND token = 'DjpI+q7kg8v3pFzL35OzMBlwKpkWqOVKKHRHS/CwehM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}