SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd24564020466e1934285ca66de4daca46eecf9ad91108df9d647c4da55e5a669' 
  AND token = 'IYJMZGfWEsgQLqShMK+34IIe32EAr/pYjqPNXWQORfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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