SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '93ba8cde5b920553580e600ce57d5586b06428d8ca17b96058384bbd2c4a21ac' 
  AND token = 'tYiWD0PjP+kbMiKuxyhktujSYPC0bN0KSxkzwUZkXvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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