SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '708962eb5672c0f4234344cb0656b98ca079a57f848b6a75535bf08f5b9a808c' 
  AND token = 'EI3mijl26HVCIMTYH2FKyg9bVfNGuhdGRtIuW8trTH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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