SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26d0971ce39bfd8fa6a42805574537cd1b90a9ed8620d140540aaf7e69642603' 
  AND token = 'dOvfDlvmocKRGhCXWoGbTliYFPrdg1G3rjW7YO19FIA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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