SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d334ab74f31856b59042ec48fcace0555ffd5315884db849da60bad50c6dae5' 
  AND token = 'cYZrk+JYlFsuypsCJsdgCJm1iY3fyZepCpe5OSFOnzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}