SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '04c6dc387fb04135a3a77c11009776bd2a5ef926c596295023a277583a433255' 
  AND token = '8nzHcF0kxMcMVErjTiKsLns8NLspe0nkVOso6MnN8sA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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