SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '911ad8afe13a820a6cec4aae39857e26dead1cf03b9ec63a07ce805be8ba3b24' 
  AND token = '8sZ3bskVvPMQ+gfCgXXffhnWj41MBoVbbmImUAsWn3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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