SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '521e916820e865f5d4d1ad24c602d6d3510363fb7477b44f95c167dcd13811c9' 
  AND token = 'PnWYc3SnHl2G+EqTXANUc/wmLtkNcqwA8KyWq4Coz+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}