SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5f4212080623a3aee36e329b05d7aaf5c297be8c23342560ae705386a3e9fcd' 
  AND token = 'mWeIYJnvBy3vkZXmwKPFk2DR3yWoOsB08NqqkWN4Gxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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