SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c399993783144a3ee31f7a30b8deb6fadb88ec85dc4ada16246786b7baedd80' 
  AND token = 'KQtZkUxIpyU5ssj+PexMkgTWk2tMyxb92DWowOVMvbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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