SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1518ac64fd91c644e3723357f76ad5b0a6cc05f3c25d697a1b32debf94e643a7' 
  AND token = 'GnWT+JVhn7cqxmZjBd5Z+m1gGvaONoo0q2AzWqGr5Ys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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