SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3633b8ada59b3a6a4787e4deefa77eed7c71c13eb927bc0e4ec543ef353e83cd' 
  AND token = 'oNkifOyUNbCPKbtPgrKJnjCE2mfwR/4qTzw+wYLxDv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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