SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51729ab86948dee3ca72858c232e265742a8e77613c68b5e433c69e7a3215192' 
  AND token = '3O24ziIYltVQO3eXWv9/vBW3ZeIcEB+WoRYXUMsb9Os=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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