SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29eadf436d02fa4be803c6dc0f345362b544aebc07806ea6994759934f6f5590' 
  AND token = 'AQsqon0vzNUPlFYMkFrRH/tdHMWHhEUUWjCawn2uQLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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