SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff392e31a4d29b7328f68df47e5852846e8becad34724743309fcdac27781575' 
  AND token = 'WYiSd1NK+zUTFuul2miuP0gepoBv/nFQhvU9B7btPCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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