SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a76e5a186098c4489accbfbc774a716085b0ee0c8bdee643ac1e1e3704f4800' 
  AND token = '2vJbxzFwr2R3eU3rrrA4RKhgKzlqePM1FqxeScYemHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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