SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c969f05f0714554324f9387948dc03522020d6e848816d12ab70b27005cdbec' 
  AND token = '/+8uCnMHsomcVd7sZNvAlINquq1MdgYiAmNeIJGYQLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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