SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b31d79d3068501efc54950129164a61c963182af323bcb690fb69fe343fcbda8' 
  AND token = 'koDAvkN0HSRkeR9i8bRJ6JZrLgYNA7IS29E1DTI6drA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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