SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f715921588dd2fc4833fd3d2699b88c2b11abcd04562ba6466ea22ac5d07c11' 
  AND token = 'cZV0CQG866leH/QbzvbDvIGckgKEmil5CRhnjmdxE2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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