SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c0685e85aeaeec7200bf35229a392c4e35cf627857a31a236c096eb5cbed487' 
  AND token = 'ShJZaasvnbFDnjBufPvZIUyaImq/J1DvvlN6/qKTSP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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