SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f4cd82e5cd6abfbde0d7de888988a3fc4c632f8791d109e3f2852235d9ff812' 
  AND token = 'rq+FSMpVwgWzR4qLyLJMQDt7IfdJ4MrYKkQxsoWuzuU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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