SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e3c8463ac5ad1f46fddba20b5b99cbc8829ee9d3ac34b34e0441575fb7fe92c' 
  AND token = 'WGuiVEdA3Un5tXHV4kPQ15vQX2+pxf0LTKh5hsI0smQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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