SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b61def00cb529291f2acc4f0dbe42bd9b90dd30e3010d9f59e751e4f239298ff' 
  AND token = '8v/Y1RURxDgUz6SfV5z+QMZKLNmCT+pBbWUGs37isLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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