SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '026684eee4e88015bb149003ddb9965af94702b1279147ed0c51a4cbfef875c4' 
  AND token = 'cDAVMzIKsNfgTR1ti3833D7/dmuTdIRJ4TQpjGQ/QwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}