SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ae576d45636fb9d31389c90cf7117fc8e0b7a8f40843c0141f03fad0451bcf7' 
  AND token = 'c8JJc+rX5FUs6qwfgaJB8jwOLn0sr/SQnuKHPmqSKtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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