SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b0ad829cfa3b52b8bd55d399dd88428dc11d7fced0f8ddaa99548530237168d' 
  AND token = 'KdZj1NyemevAvOfbVG3dKmKyqVokNTrsISDmf+phR9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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