SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6b98021f2b697d74d5d839c833c2e83bdd91ec2ddf2a23a331dd95ff15011b2' 
  AND token = 'iYuYVKLWzluepN7FR2US3SQnZGICloC682HUgGfUFkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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