SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4dadd1ffc32aa755423347722297cfad50a94d07f0e9a8ab89da32292a9e859' 
  AND token = 'PaIMWb7GCP2fciRtvfyxuLBkKYM9i6UbRsmkIbnFCcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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