SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57f337935d784337ec4a3c5d06b5a94f200f43b96261a5abfbd20a04cda55746' 
  AND token = '6XDZhETNUFcHTA98K4WJcx+Y0ZycnTL35+FxHvcC1OI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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