SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a26709869b19727a62bcd936574da75182deba76eca73796b72a52e6ed5e8b34' 
  AND token = 'NXDr6OUggkK9rDUxuFsSMLykrzdanBEF3YnWBoaBs+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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