SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb5c764735096e94238b317ea4e23ef87310ff731924341768d8c8b1b304f487' 
  AND token = 'Prtl/cBIINoPeE+7z64HqqJDtrOS5D7nRYKubzKy1yA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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