SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cba51b88a7c2bb30eadbcd544f20c9e44252baca6314e0ec6ca15735922db1f1' 
  AND token = 'rBSFdohjNqFxTZ0i8kAKxqy4DJlg9F3MheldEECDolQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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