SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cba48df59eb4f3f7f78e370c68abd297e5e1ab09f16980a07037b75b4de2d96' 
  AND token = 'ujQhc2Q8n5htfRVCE23/yIfrP17NHlGTV64T5upx2i4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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