SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f88c960667951cd765e76f52c35dcaaec3b8b6122c625c5701486cd7af0038af' 
  AND token = 'nec3UWBCcqromZxpVbSwfwjVVW0CBGm1LAAdF5I/c/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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