SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '947d974f25fa95ac1c7feaf40d7f237c80ff79eb5a585659793df823c022e8e1' 
  AND token = 'JImAgiER08VPo4GYgsSY3rVzKRyuL9RAMbLFmcqMhhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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