SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d38c4a2c66dd173143a088549e96e822e5cb09bd2168b32ee63292425a475ec' 
  AND token = '5Hg4v8TvaTKwhgsTBt3GvZpjz1JwxS7kDX28k/F/Rh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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