SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb4ee0322b1c8a343349cbb17bd97195f5c6397d8a4887e22945c88320bff250' 
  AND token = 'vgGEU6CWlBpgRhHmZSjJzoBxewBRXsCbK56teokiJNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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