SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1d9b9051394239201bbb6c49806beec40e43fb97073dd597cc13ca942d24b25' 
  AND token = 'CzKgnqDTVMmff+1ZD0uiWyVOe+pTKbfftBsEJvcO9ow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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