SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dea7fbaddf17440f713c059af23df75e018ff382b069be10f3fef201bb8594db' 
  AND token = 'TJZg1FbutXdu7QvC9evCe0RceEn+pfkoip4AjsCizrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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