SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c104a36c85073483ef0060ed021271dd948054f559a02904bdeddcf61d834dd' 
  AND token = 'EsyBhHWZywNTjIatN9TXS1mL/qeBhdbUp6lUDjuX5lY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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