SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c891122adcc25b381562f8bdf994cfee55fe85996859329911d7873d3b70fd41' 
  AND token = '7w2xq8ozx7nIPUadNCqj5ieZbwRyF9xJAjp31JmtMxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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