SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '102df9f73609a5b55e93b3615ec1abfae7f917b3164d3016e3dd6af65a10dc22' 
  AND token = 'n2IaiX1eaI+YIiirtSt4j7mQvrgh3DTZLqfNWe+jOlM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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