SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28dfbee4258e28dc416e98bd0f1c6cbc0e68a3c50b0f40d701882f39ed3f98de' 
  AND token = 'w8UndkXh2UMYfowCPhImBPdWZM6uOMBcNCLTjbfAeDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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