SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f99977767351136859378954ce60b49801d3a992be284c760f420ec0481a7a0' 
  AND token = 'uinL4zO5xmCxJ0tXlZvlIfjzDVE+wtSNUbFsRAUDzY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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