SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18af47b73487aab5cb21dda8a554822cf7f02a44e1d06412456ac7a5fe15b424' 
  AND token = 'Y5jNBuKAYMzSYjJJDCp2Pk92302TUZWMciUaxCCIf4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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