SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b4bff4799383a686551a2f456aa37b055205c09371580042f6b476f1ac3e98c' 
  AND token = 'vvlFbSMO/GSh5b3C/SrWpFHmZPvhozjhF0+EjxBnq+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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