SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '78f92e3957c313dee495be8d4c2a09ff6de5753c245339340d577a3099ffb2ff' 
  AND token = 'I9/eXaET883jWPrClB4tYgbYX3iQ96/Zhgk+CrwACA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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