SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c73a1875f1204cb3a27aacdb8355f4b46359b31ee51845a68338d0e724b28c16' 
  AND token = '2Q5EmJjyOTuOLm6gTwPk+XrhDDRJgUh4FfP5PX8kUsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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