SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'abb68289533de2142bda59d20988d45a25fdcd8f55d67c2fe80a1bc7349323bb' 
  AND token = 'ZuGO3QlIA5bjqWlSxwMXbQqnR3Tk+zs71XwqmVdqAPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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