SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4262d53a5695080caf408870092ddbfd6aca00a9b388026faf4b5e4b546c073' 
  AND token = 'PQnmOFV+08UbsrFJIGIDQDxaK8QMnaN7qkXUqCjfMlw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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