SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '79b034bcd1143649ca95467bb3b7bce0837629f6a092554e7cae993f33f11e39' 
  AND token = '3YmjhZzRQ2yk4AedJ59UsuvklphfASdWz7s+z0T0nSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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