SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '996e33316ce291fca27d6f90584498ec061db0233779115a5a728c84465f0b89' 
  AND token = 'IWMOoMYUeMMlLZThE+wYuYeBwFkJxMbKymJbmVxuT4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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