SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0f87c147b1b54629c326aeafe90edde8e27e104d58808c68daf1eb0c30790b2' 
  AND token = 'bELovOUOaySrae4X35Oj/YoV1munNSh++Tz6jv7dCiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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