SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b1cc13f64cdb29a476d379dbe6031cb6fa145bdd09a4725ccc159cc2b08cd3f' 
  AND token = 'rVqxx7fyrDwtkEYaCe2amEhDgwXdrs/buI4n6X7jIT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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