SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85c12102f1cdaece29db39de48e3a29771b9a37434e243c2b7d2fe1246a12ac8' 
  AND token = 'xnFfakcSVWbDqwTSmeU5ZEMV4fPH2+ZdUANvyBK0FVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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