SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27b36146fc0d92546669774888fbfbe2358dfd2a73a608679f860b2bb12cc277' 
  AND token = 'Zfcio40FyS0rzPdcWn7nNi1ItGfTZrANAOejcmcYtCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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