SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '541baa3e952e9e719214126841f6bf02be5a45155b68651bc17208d390aa3b06' 
  AND token = '4Y05eJI+FKVPU7rjQ2Dyuwl4UoMZ7EHqvi6oFvITYlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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