SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59fcec9abc1b30da659595382d714992eee910741d83dacf5cb56456c165e6a8' 
  AND token = 'USxAyx3hxVorc/VPVlCIRkFkvts+w4a+OPYH59cJVnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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