SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5600838d04394ca2beceb8de450368e5ec6073d00d85914266a735073ece22b' 
  AND token = 'KKdFz+amOYtAwLr1FOdh/1v7ETvtApmxNe+xaHWwlHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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