SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a51b2b0f149016babcd04fab0956d4e3b59d99679d277a6d5b7b0ccd3e7209e8' 
  AND token = 'RXvAlLtSDAmPa4NjaOuLKJ/++ZKyNYtVYae6JKTRcbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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