SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '787e233269891bb38efc2fe47385007ec376e84ea034a2ee2e37251f7ef2ce3a' 
  AND token = 'xEn3WFJaOZOhelwcw4tgGNXUqlMBbeet288vl8b/tk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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