SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4dd1696b670109826ecfdd9d5726668d5f385322581fac60ccb6935cde5c137' 
  AND token = 'Kh1T7c/lZVYCS56gXGRxUSBTj89XsRghvdyseaJlizw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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