SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18df7e29221b91e1fdce3baa3679e82d6233e1e69a7f2930065ab4c764f4016c' 
  AND token = 'etQDtZQsTCdZ6yJVp9AbtXC4Z6jNLRfRMtPNdHt/Jpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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