SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9fecd50aac023c39e948168318981a892581dd2842fb9968cac840658077ad0' 
  AND token = 'ZrUzb5m3WOgJbu2LPgHmvsoRX3hrLX6wf43pMmJIqJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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