SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40cf76505e49812fbe9108df67595ea33f4703beda4beb49dbf99f40e24234f8' 
  AND token = 'N/PBbJ6+Ay/BoZu+CvMt6YLOLjpYO28/vv2tz/lh/dE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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