SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a37f55566db58dcbdac8f4bdf021638babc31a78e819ca36a233532a4ce9aa84' 
  AND token = 'oGQcI7zmijAXqjrkQNy1MuOvFowiRhBpmGu90IcOExg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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