SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '100638e39d12ee975a868edfac5626db844418cba7515aa4c99744520be86618' 
  AND token = 'LkUw7WQJHFBq3QfpJNYSQVMpvfV2e6GwCxv4uQSDRyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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