SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79d1b34904efb82b9be27e7a60abd54d63c37862f28fad4302c620b5f5ca00db' 
  AND token = '3+olVj7DG0z8g/rFFvrOm/pJzEUp4cB3Tsj14hxavrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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