SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff4e6338d666fcddd9b9c71f505c9bcb7b70720d1b71a2e43bf987543aa32da9' 
  AND token = 'ybQ8UKPJghBKcvaVAMy/gwxw/j7NmSOcibl2UnBeHf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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