SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89792ebf688bcefd35976e8ce59079fedc1678b07d677a6050f09666588fe9c0' 
  AND token = 'HcR7phTomWot49qaUadbymGbSBSHX7sr+bi1ctIaKfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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