SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '811a025144b78f695726c2cb2891388896f10437676d9c87866e1cb4954730b2' 
  AND token = 'vwYeiqjujrXQrkSMItTt51qHeD5KcpyyX8RtS2E+UFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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