SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fc9508c7ff384b89be3c5d71c80ff95ca5e54deeb1c3f0d3f51928d4ab85872' 
  AND token = 'SHQQamvIJxJGThbbkiHlr+kh5MdyJBtYh7Oujbh3aTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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