SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'e53addd46e389adbafb090228f9abac822ba9071ea56081a5e3603a8c0c0615b' 
  AND token = 'euI2PnPD8pnqjLh750lF9C+UlY+HL+14MrSZs2ltJ0E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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