SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b261b20939408d06605c8c9cd52d4850f1000984b8d699a3dc5558acbe6c9460' 
  AND token = '1uaDjoc416piegKHQUi8/4U1oWrbIn6weaT0l86CmkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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