SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'dcb1bc6580a24c61fff12a88a4a73da9765641fecdbf32697837e00db3e97303' 
  AND token = 'FPnHUoRocy7dxkWLDWRvxF8glctkKB24wURpPAjXQTI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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