SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c31134f2a42c6ddb2b007fdc89b2044c7be708d3054836f6986340baa5cbb7' 
  AND token = 'hJuGnXGmz1X3O+iW/kJunZF2oZiOKWGDoV7QgMiov64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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