SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '116268f8eac87a8d1a286e2636d042fe6824c5378bd4e43f80c37a58254b4367' 
  AND token = 'fclBq+sgn8Lp9JqgQfbMLCsUwJzIDfo0vN16G8FuVIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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