SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90db6498191166fe43c136eaf0f941440e97ec144e5aa0920dfa816b14867edb' 
  AND token = 'A1Kxlq5FTG34FvlGgZJuF8bPhbbLj1kDG7LrplKirEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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