SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2c4f296deb8e184d0a329e5b15b4eb938238a205536a5c7a2844717c3cf9474' 
  AND token = 'pBJSFgf5H7qAv8Lh8pTqG11WjZn8UjPDHQmJh40g338=' 
  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"
    }
  }
}