SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1375d7c2db622c06ee92edd33f31030ea334137a2823850758baff628c4a62e1' 
  AND token = '6SMyXsxVfuDRnjgiJH8fa1g5s+AEw2WVG0v48Le6TXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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