SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8f1086916ac4147f5ae4bf1c686e55793d280ce9a0d0e28a28dcfd2cbdf12798' 
  AND token = 'fl6Hxpx8rl0uivn9WH43DkoOx3PWWbJsOvO88bCay94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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