SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f191f1f798f1f67b6c3eae46f033e140e900439055f29230985eacdd29b3d9d' 
  AND token = 'ZCUQhRO/mGvhewGvMQkI+AXwk6vSbCwXmxBKr97+/9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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