SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4cc1895743bebc0d46fb9a10a25ea06ae8d812f11dbbf2a14dfa3106fc4bd6e' 
  AND token = 'WQIguE+ZNKtaX2EIEkAwOymPGT9CyPG6OI1sZo0PZAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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