SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f2f80a312fcef676fd66c5f44e9fcfdcd24660933bfb532c33a9d5dff079f7e' 
  AND token = '/Z9JGfhjTVqIfgQbtazYKFdgUleY/9TLXM5IEulUMk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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