SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0fe598ae0320ba3685ec64910272a5e0fd949609941f605fc0a3a7715239e39' 
  AND token = 'csViwDMY6iwR9+TtKx9fQLgBATOeOhs58rAnr0UynnU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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