SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55509f78cbe227f812723490d03231ff479f1b7fa50b8202560473727b51cd76' 
  AND token = '/5SF1Q2ih9iZSKkQ+Hcl6romw++BhKtTU/wjixXVZJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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