SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ab54f99f6de3ba4eb5493bbe94592b229211c21a7840b606e669f7ab8a0c23b' 
  AND token = '8I/yQcWxZutliHFAHtWGqy1cbci87HYuvCO8atWAZs0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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