SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26da3e7805735782ce538665724f7bb6e7ca75fcce85c1841484af5384a4a34c' 
  AND token = 'bzOYODObUS2IQrbdLKHlq82lQKhxguQpaPzRJdE2wQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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