SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce91d9c519a7975d90b50b362aa5f4d3b80f241a9fe2761ef01c83bd5cef44e5' 
  AND token = 'GZbjkD4UlTVYfS30FMccVQSQFFGIMHWN0JYuX58mVRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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