SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a9cf3346ab66440ec698eb3f6cdd04ddc730226ab99cbc3b53f973a332057bf2' 
  AND token = '8ZxR+GBCZAV2L40aBrWAAxNOA2m36Iuk2ItTehQ4F0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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