SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca68bf08bfd4f4add99bf3ef4c8fd035fad889b20dd0c2a0f57396a8197a3038' 
  AND token = 'r+Lzw1KI2xyVNwf+bdQHYJj7g7XOvjxCB/5m9k3xQXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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