SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d6fd5f674f4de448fe2c6db9348fa9c792adb9fb115d85b5104de1369c390b7' 
  AND token = 'QrauN2hpLFD14n+a+BvqRufACNKwjM47zeahWVN86Ig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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