SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '090dec09a4197a88b07018b5efef594b0d353fabe6f97adb00892426e92231ab' 
  AND token = 'QPRXJEFhDTfoew4tIOdZhMiK+/ODSkV86zlDKo7+mvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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