SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '390eced020ca1055874c8511f20ef4fd391f26ed91b3671ca044b6da6e7fd2d5' 
  AND token = 'KI9kIoWqIrre+zsm/YAt9L5FqP/4h/Jf5lq1UCk48e0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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