SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0f8a7971d2f1bc3297facc1e36702e0faac4c4c14fd0ca2a8f0c00ef36da13f' 
  AND token = 'nKxs1mXVZU0Jdnl8qIwygfKd7MYQLqzHafBF++e2OOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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