SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'add02e3671c6be4285c76560620bf04268224e808a7fd7d1bbce87ffb41cf833' 
  AND token = 'OBtkd6W9RssX7xaCgnfSiqM415WaCFcsETonhCbTQK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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