SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3243d4a52c96a2c23bb2e44850b85f6a407036623f581894c7763986bc476e87' 
  AND token = 'QvhpjEIAgHvFJvQj1UtvECx8kxZbdoSCVZMYDQBGu4o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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