SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e3b0add53b49797e862bc3eb2df8d32f0e34fad03581f13b5aae643300b49aa' 
  AND token = 'YkNYct+GEVM/kGmamja4RAzZFXvKXdCEIXd21ysYjYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}