SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df2b4c4703e6fb5c438a71d2cc64f921df65dd582ead3f616fd50998a0a9416d' 
  AND token = '6ruuw8Obh7R5n2bemV21ckVq/h/rVx4kDH5Siuo+69w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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