SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a5c5deeb86f61069e00228ccb7ee159529428e93cf0666e9ec325f09553d3828' 
  AND token = 'qv/LnGTcKqFa6z2AVOWmmwRS0hz+Ykuhm/zkIiUx1ME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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