SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8a4bf7e3625d208d3df6a393335f9eeee2388022a4c8ed887aac29328d72a88' 
  AND token = 'FpKwmigxpXqTi9u48emBzCosnxbgo//6NBwrDPFBCls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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