SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '503af2882ca67523e38378d8a2977afe7a005b22cc2edcbe1e041074cdc3e29f' 
  AND token = 'RAMO7CyxYTW4euHbRdOod3eI+7u7SA1Wlh6mgvXYwhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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