SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '864f863e76d62fe21ab3e5f48f5961a01d49a5921566c021360a6d14b4cd6e13' 
  AND token = 'pGmV4EP/DsplKOKaE6JJgm+EQjNYAk0YpoVqH2S+8Ps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}