SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d509aa9b5f387f820eab535e533a52b08a0da83191c8d8d9f156f26173d7be1' 
  AND token = '/QIUi981WYNx9moNCshKVVxp1mcyfLgmR3s0Zctg5Ho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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