SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91281e23abfcde56d0c7bada1cd3478fd37c5f828b8326bcae5e952429a0cf36' 
  AND token = 'SUlv5u3gMMxYz38YLeEMpLhQHVO9RZ+GhWg6AHVhtp0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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