SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a218f191554335476ef269e33e3fbaa0bbfc20beffc94c2897fb68833c0d01a' 
  AND token = 'DVoThLXuhfacFMu73MHLU0Cfjai0KTa+HarNA7KOujU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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