SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc5604ce317e9ea44a8a1c23b2421992b6abe6744de25853f33029188aab028a' 
  AND token = 'JchWwTRAm/e5JSRODeCU+bHrMvHY4msRTQMDFW0JbEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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