SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8e5c3204a549a7f85c1f551be79e175672e04ff531c235427babe92e0b0d83d' 
  AND token = 'uTLMKrbu3LwV/+MVnLYzuIlR/YWZPYVZEVKOOqXnHQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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