SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8d6e495b1908d96d3fdd68c85767ddf66a7af93477a0638516fb65179e766de8' 
  AND token = 'B6HDNbFyI/YKA1YgtUfpGisTiW+NEnhfpReLMkEj6HQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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