SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7d9eeeb99619ad9450bb99f7dc188be15d30a2df6a79c777df06e8e531c7034' 
  AND token = 'AiTQr5xB+kwyMptQhDpdTgbEsRn/jfX6SxTKfPoyVuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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