SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dca0bf8529d76d411cc594b1ff841fc8ed84d668ae7377cf709aed1595486bbc' 
  AND token = 'jhNgEv4bxdPOGp2zNVP0CBmlBYlpX7my2XFJDdgNPuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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