SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5c504cc20063ab6bca8d59ce9f95f0e746c413fb071bb4376b65cae4df41f19' 
  AND token = 'LuZ6IvoRrZ1SLyXdLmO0P3WYtyO65wjEHOHrJqUqHnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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