SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f689058ba801fe12c93026f8a9cd014c08244c12417e7942937a6d16964ef8db' 
  AND token = '98b6G+OFMra7zLTp0FBNmxa8LyLTpcbr8ISjlU/mjng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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