SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a97adf70523e840517af979ccb977dca41831f856e6b200fa987bff93a709382' 
  AND token = 'JqB6ZTigATZRV/+W9ppNLjE3NbKBFeHT9Y5UjZ+fyYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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