SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2a8ac61eb14dbaebd4860ba8323aae160836883adeda8b46dbea94c5b84d7593' 
  AND token = 'GUa/JlVOiTaKNtV3tXBnNffkENdkufOW6seF8Sayug0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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