SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbf8b878dc393c9ce08722a3703c24eb876468f398723b8143169ecaab46f359' 
  AND token = '+ROjrRf6CY/1RLZcHVvTDI13FLZuN5qaEgG7XactHRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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