SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87bc6abe8929f68728edaaac953237bb943f93097df0ba3355eb18e59a36346f' 
  AND token = 'PX/53jRRhZrmamjucV89SBeyhwha4I3KuHb1ICLupdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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