SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3f0c76469815880686576c1e9aea09f6d3b1d582f2544d36a80fc9678f74822' 
  AND token = '3wwT4CsaxR7vGFyorkJ9S3e/i3D43glLI7QqP3c09YU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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