SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a3bd026facdd160b622d32f59e82c04530cdafc805f5a6e7fd9bd13878d2cce' 
  AND token = 'W5pHXncy+5j1Tv3JIo21ZfUFe1Zn6ky2g86VAGzVOuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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