SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '874307bdbfeb0e1489e6c119e56b17e29909158d1c48fe9dea08d7e4744a5c71' 
  AND token = 'BzaJ9CAicPW1rYjoPnE7615YwLjyETGhfZqGivJcRtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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