SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6d198b78e2664ae43306d6375436a4c3e2a4fbaf4b5452cf7667c32cc1a81ac' 
  AND token = 'Hyb2CNf+DytDodMGPDeqpUKZsznBYw+wUPlIBIzEvKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}