SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '174b1ce823a7883530a49e1884c3c2858b185ad40bb025cbbb0cddfba7a480c5' 
  AND token = '848+5rhhNJCQGGtygOGzI8RQTzEBshFGxURbcTavGlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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