SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f908b802d2a2bc8330eff9a76fd9fbc9c56cbd061d56a9e9cdcb4ea13b2da4e4' 
  AND token = 'EJeGXv4MFwS8QGiNXLshA/IUHqjH23jbyArsSTDveRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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