SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e35b507a349be64d9802c19626f3e750abdbeabbecf235dc811df1b7681ae32' 
  AND token = 'pdDx3YtLn2qEb5UrTybDTFYyPoMvbmKzrCP9cXmnjyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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