SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d4ff6d887346cf73e66b6cd4bd684a5f1e7cbb791a629e70505835a9858afdd' 
  AND token = '1qznvbzOUwbO9gKUOW+JwgZWSkuFzAQLLZzIOBlgVWc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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