SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88e306dd677647308f02bce757bf58739ecad1c53f8fc404000d879c75a3366e' 
  AND token = 'mtSarT9omZQuyBp/ZCgjC09hfI45vjOMd8OrYeBlCMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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