SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a81c54d08bb690fa9138887d28cd139692491e9c03ae51e88f300b7125b228a' 
  AND token = 'CNZrqgwtPE/R5oa9NKpJdjLggFGCKMZJoMST/wkCF0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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