SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4cfe48e0f03147d131cfc84fe5c2d2a0c254362f7354f2daf1d538f81bca804' 
  AND token = 'cRyI8HioyMwk3i/82d0nZy4v8SG2WhXlZJ9+dorjuxE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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