SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f81b935a79ae1fadb4407661f4aab4fa9d397d90380fbbbc8016cd0b14d808a8' 
  AND token = 'qyFbtGFCHGQm1rWAIs4+OfT+wvbxaDiKPrpvOQB0cz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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