SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b96b1a8d2cf25c6afc371b4e2cb0bb59a2590bcfef3ea92f5c64a1eca4ade20c' 
  AND token = 'ek4spN0ZDCruveffPnin2TZXBWmh2Z2pbiYiLwi6PTg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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