SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8693bbeefa324e8d0ff1cab5136a00b193b4b14e8479ebd423b4d6ee411c907' 
  AND token = '8rs+KHFMlwsmBCYTGHuCwKU+iVnkvzPsLkNXvKvcRHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}