SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a3ae91acf894adf5f847ecf85133ed563cb00dfae9215bfab786915d6c7d5f2' 
  AND token = 'tvLh8znJzZs+eyQFCowR7E/h44n/aNNYoJRgiaWYyJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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