SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50dfc746bc0f78e5501472d4bdbd4ec0dbe25b8564e3810f48c85313561f9a27' 
  AND token = 'j6H3v7yjf+opcOBitSpCiuqyA+jYTDlMyB6WoiA5s3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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