SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b216421de0c694e6cfd701faefc25f62f6127e3b4bf4d102617dc9b4648d287' 
  AND token = '6Sgl5x47LyOanqqyTgTGt9CiLIRstFXMOvJ8gaVz7UM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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