SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '842a793c098f45d25601e5e1397c1581e2736e99553e3c1ee1615ff8420eef54' 
  AND token = 'WNC8vGRquU4yxKL1rSaHb0V6tNoMVRW5FKHxyuq7Rj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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