SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1f844b0c7d5183e29664318d5477faa20e270df378652a83b77b241dc171eb4c' 
  AND token = '+ffyUFSMWdYx78G8LVtyziUUViWCJbOJWzsIuIS1Yg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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