SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd519bd747cda4ca95fcffa431ff7d9c9a4cd7d805a0d61496645920f44688dfd' 
  AND token = 'ERce+hGU+jB4gQtttGmBLEdlXMeIyAqXpID35HOOPU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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