SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7b297a5f64430aa68e5135359614d708db68344c7dcef7a19881de46a47e2ca' 
  AND token = 'xigtQaZcss2Zp/0PDwZyFzZlbUiDzmLbWn016/RcSj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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