SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '935eb399cf167340d07382c892c261167246e12004a7298b4cd47bb3b3ae72e4' 
  AND token = 'xZogqqDIO+VoU0e2xrPIEwidaptTui3ZOPcxewxFvg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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