SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8437ac181710ff335bf871ecfe37acf4c769d615c052bd24852eee534e088353' 
  AND token = '9DmjM62UZDeJSy7FcqYreJOOJiUjVQ10AtJFlAzSJUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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