SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f328e10390eadb86ad470aaffce6978d6eb60c5ea2592af3c7f7655c0fd9a83' 
  AND token = 'JnRRVzDGZFisjtFZphgNJhg7eUwBArp3pIbwDOd6wfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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