SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31462f782043f606052c18b9b1a1caf4c8759f58420891e98db7d57a5c823e95' 
  AND token = 'Sd6J+Ut+v0XQ+hJYdTna7EODaNU2hQ+Gm0lxsTYgBFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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