SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c51a6a02ad0cb42d4f20dd32dfc40a4abe47cd7170f94ef81af31276c51a763' 
  AND token = 'NbRM/h3yZEFlZz1pMlPJwYzyofcBhqFTVBT8NhXHqB0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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